The House of Representatives is engaged in a formal impeachment inquiry of President Trump. It is focused on his efforts to secure specific investigations in Ukraine that carried political benefits for him — with indications that there might have been an explicit or implicit quid pro quo involved.

Below is a timeline of relevant events. We’ll continue to update it throughout the impeachment process.

2014-2015

Feb. 22, 2014: Ukrainian President Viktor Yanukovych is ousted from power during a popular uprising in the country. He flees to Russia. Yanukovych came to power with the assistance of political consultant Paul Manafort, who worked for Yanukovych’s Party of Regions.

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After his ouster, Ukrainian officials begin a wide-ranging investigation into corruption in the country.

March 2014: Russia invades the Ukrainian peninsula Crimea, annexing it.

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May 13, 2014: Hunter Biden, a son of then-vice president Joe Biden, joins the board of the Ukrainian energy company Burisma Holdings. It is owned by oligarch Mykola Zlochevsky, one of several subjects of the Ukrainian corruption probe.

May 25, 2014: Petro Poroshenko is elected president of Ukraine.

Feb. 10, 2015: Viktor Shokin becomes Ukraine’s prosecutor general.

Sept. 24, 2015: The U.S. ambassador to Ukraine, Geoffrey Pyatt, blasts Shokin in a speech in Odessa, Ukraine. He points to a “glaring problem” that threatens the good work regional leaders are doing: “the failure of the institution of the prosecutor general of Ukraine to successfully fight internal corruption.”

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“The United States stands behind those who challenge these bad actors,” Pyatt adds.

Oct. 8, 2015: Assistant U.S. Secretary of State Victoria Nuland adds in testimony that the Ukraine “prosecutor general’s office has to be reinvented as an institution that serves the citizens of Ukraine, rather than ripping them off.”

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Dec. 8, 2015: In Kiev, Biden tells Ukrainian leaders to fire Shokin or lose more than $1 billion in loan guarantees. Biden joins many Western leaders in urging Shokin’s ouster.

2016

Feb. 10, 2016: The International Monetary Fund threatens to halt a bailout program for Ukraine unless the country addresses its corruption issues.

Feb. 11, 2016: Biden speaks with Poroshenko by phone and again emphasized the urgency of rooting out corruption.

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Feb. 19, 2016: Biden speaks with Poroshenko again.

March 29, 2016: Shokin is ousted from his position by Ukraine’s parliament.

The same day, Manafort is hired as Donald Trump’s presidential campaign chairman, a role in which he will initially focus on securing delegates at the Republican National Convention.

April 14, 2016: Biden and Poroshenko speak again.

May 12, 2016: Yuri Lutsenko becomes prosecutor general of Ukraine, replacing Shokin.

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June 20, 2016: Manafort becomes the head of Trump’s campaign after campaign manager Corey Lewandowski is fired.

Aug. 14, 2016: Ukrainian officials reveal the existence of a handwritten ledger suggesting that Manafort had received off-the-books payments from Yanukovych’s political party to the tune of millions of dollars. These payments will ultimately be part of criminal charges filed against Manafort in the United States.

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Aug. 19, 2016: Manafort is forced out of Trump’s campaign.

Nov. 8, 2016: Donald Trump is elected U.S. president.

2017—2018

Jan. 12, 2017: Probes of Burisma are finalized and closed, according to the company, though Lutsenko later tells Bloomberg that one sale of an oil storage terminal will still be investigated.

April 21, 2017: Trump for the first time floats a debunked conspiracy theory that Ukraine might have played a role in falsely fingering Russia for its 2016 election interference.

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“[The Democrats] get hacked, and the FBI goes to see them, and they won’t let the FBI see their server,” Trump tells AP, adding: “They brought in another company that I hear is Ukrainian-based. That’s what I heard. I heard it’s owned by a very rich Ukrainian.”

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April 28, 2017: Trump again brings up the conspiracy theory in an interview with the Washington Examiner.

June 8, 2017: Trump’s personal lawyer Rudolph W. Giuliani meets with Poroshenko and Lutsenko, according to a later-released House investigation.

July 25, 2017: Trump tweets about “Ukrainian efforts to sabotage Trump campaign” and asks, “So where is the investigation A.G.?" — referring to Attorney General Jeff Sessions.

Jan. 23, 2018: At an event hosted by the Council on Foreign Relations, Biden describes the pressure he applied on Ukraine’s government.

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“I said: ‘You’re not getting the billion. I’m going to be leaving here in, I think it was about six hours.’ I looked at them and said: ‘I’m leaving in six hours. If the prosecutor is not fired, you’re not getting the money.’ ” Biden says. “Well, son of a b----, he got fired. And they put in place someone who was solid at the time.”

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May 1, 2018: Two Soviet-born associates of Giuliani, Lev Parnas and Igor Fruman, meet Trump at the White House, according to later-deleted Facebook photos.

May 2, 2018: The New York Times reports Ukrainian officials have decided to halt assisting special counsel Robert S. Mueller III’s investigation out of concern that doing so would harm their relationship with Trump’s administration.

May 4, 2018: Three Democratic senators — Robert Menendez (N.J.), Richard J. Durbin (Ill.) and Patrick Leahy (Vt.) — write to Lutsenko urging him to explain that decision and to continue working with Mueller.

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May 9, 2018: Parnas posts a photo of him and his business partner David Correia meeting with Rep. Pete Sessions (R-Tex.) in Sessions’s Capitol Hill office.

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That same day, Sessions writes to the State Department seeking the dismissal of the U.S. ambassador to Ukraine, Marie Yovanovitch. Sessions says he has “notice of concrete evidence” that she had “spoken privately and repeatedly about her disdain for the current Administration.”

The two men commit to raise $20,000 for Sessions, according to their later indictments.

May 17, 2018: Parnas and Fruman contribute $325,000 to the pro-Trump super PAC America First Action through a newly formed business named Global Energy Producers, which is supposedly a liquefied natural gas company. In their later indictments, prosecutors will say the funds actually came from a $1.26 million private lending transaction that occurred two days earlier.

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May 21, 2018: Parnas posts a picture on Facebook showing him and Fruman at breakfast with Donald Trump Jr. in Beverly Hills, Calif.

Late 2018: Giuliani speaks with Shokin, according to the whistleblower complaint.

2019

January: Giuliani and Lutsenko meet in New York, as Bloomberg later reports.

Mid-February: Giuliani again meets with Lutsenko, this time in Warsaw, according to the whistleblower.

March: With Ukraine’s March 31 election looming, Lutsenko begins making allegations about the Bidens’ activities in Ukraine. The whistleblower notes that Lutsenko works for the incumbent, Poroshenko, who had been trailing Zelensky. Zelensky had pledged to replace Lutsenko.

March 20: In an interview with pro-Trump columnist John Solomon, Lutsenko alleges that Yovanovitch gave him “a list of people whom we should not prosecute.” The State Department calls the claim an “outright fabrication,” but Trump promotes the story in a tweet.

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March 24: Donald Trump Jr. attacks Yovanovitch on Twitter, saying, “We need more ⁦[Germany Ambassador] @RichardGrenell’s and less of these jokers as ambassadors.”

March 31: The first round of Ukraine’s presidential election is held. Poroshenko and Zelensky head to a runoff.

April 1: After speaking with Lutsenko, Solomon reports that a probe into Joe Biden’s push to fire Lutsenko’s predecessor is underway. Lutsenko tells Solomon that he wants to present his evidence to Attorney General William P. Barr.

Mid-April: Hunter Biden’s term as Burisma a board member ends.

April 18: Mueller releases his report detailing his team’s investigation into Russian interference in the 2016 election.

Separately, Lutsenko retracts his claim that Yovanovitch gave him a list of people not to prosecute.

April 21: Zelensky, a former TV comedian, is elected president of Ukraine with 73 percent of the vote. Trump calls him to offer his congratulations.

April 23: Giuliani tweets about a Ukrainian investigation into alleged foreign collusion by the Democrats.

April 25: In an interview with Fox’s Sean Hannity, Trump addresses the suggestion that Ukraine interfered in 2016.

“I would imagine [Barr] would want to see this,” Trump says. “People have been saying this whole — the concept of Ukraine, they have been talking about it actually for a long time.”

Late April: Yovanovitch is summoned back to Washington “on the next plane,” according to her later congressional deposition. Once home, she says she meets with Deputy Secretary of State John Sullivan, who informs her that her time as ambassador is being curtailed.

“He said that the President had lost confidence in me and no longer wished me to serve as his ambassador,” Yovanovitch later testifies. “He added that there had been a concerted campaign against me, and that the department had been under pressure from the president to remove me since the Summer of 2018. He also said that I had done nothing wrong and that this was not like other situations where he had recalled ambassadors for cause.”

May 1: The New York Times publishes a story tying Joe Biden’s pressure campaign in Ukraine to Shokin having investigated Burisma, portraying it as a potential liability in his 2020 campaign.

Around the same time, former Ukrainian prosecutor Kostiantyn H. Kulyk tells the Times that Yovanovitch had thwarted his efforts to deliver damaging information about the Bidens to the FBI, by denying his visa request.

May 7: Bloomberg casts doubt on the Times’s report, citing Ukrainian officials who say the Burisma investigation had long been dormant when Joe Biden applied pressure on Ukraine’s government.

The same day, it is reported that Yovanovitch has been recalled by the State Department, two months before her scheduled departure date. Democrats allege a “political hit job” aimed at creating a pretext to remove her. Yovanovitch will later say in a deposition that Trump pressured the State Department to remove her.

In his later, July 25 phone call with Zelensky, Trump will say Yovanovitch “was bad news, and the people she was dealing with in the Ukraine were bad news, so I just want to let you know that,” according to a rough transcript provided by the White House. When Zelensky thanks Trump for previously warning him about Yovanovitch (exactly when that occurred isn’t clear), Trump responds, “Well, she’s going to go through some things.”

Some time in May: Giuliani meets with a top Ukrainian anti-corruption prosecutor, Nazar Kholodnytsky, in Paris, according to Kholodnytsky. Kholodnytsky, who had clashed with Yovanovitch, has declined to comment on what he and Guiliani discussed, but he said the Burisma investigation should be reopened.

Also some time this month, two Giuliani associates travel to Ukraine and meet with Ukrainian officials, according to a report cited by the whistleblower.

May 9: Giuliani tells the New York Times that he will travel to Ukraine to push for investigations, “because that information will be very, very helpful to my client, and may turn out to be helpful to my government.”

May 10: Amid an uproar over seeking foreign investigations that could potential tarnish one of Trump’s 2020 election opponents, Giuliani at first defends himself.

May 11: Giuliani cancels his Ukraine trip.

Lutsenko and Zelensky meet for two hours, according to the whistleblower, with the former requesting to stay in his position.

May 13: Barr announces a probe into the origins of the Russia investigation, responding to allegations from Trump and his congressional supporters who say the investigation was a thinly veiled effort to take him down.

May 14: Trump tells Vice President Pence not to attend Zelensky’s inauguration, according to the whistleblower. Instead, Energy Secretary Rick Perry attends. The whistleblower says it was “made clear” to them that “the President did not want to meet with Mr. Zelenskyy until he saw how Zelenskyy ‘chose to act’ in office.”

Giuliani tells a Ukrainian journalist that Yovanovitch was “removed … because she was part of the efforts against the president.”

Mid-May: The whistleblower starts hearing concerns about Giuliani’s circumvention of the government’s official processes as regards Ukraine.

The whistleblower is told that officials, including Special Representative for Ukraine Negotiations Kurt Volker and E.U. Ambassador Gordon Sondland, had spoken with Giuliani to “contain the damage” he was doing. They are also told that the ambassadors had been working with Ukrainian officials to help them figure out how to resolve the conflict between the government’s messaging and Giuliani’s.

In the same time frame, officials tell the whistleblower that Ukrainian leaders believe “that a meeting or phone call between the President and President Zelenskyy would depend on whether Zelenskyy showed willingness to ‘play ball’ on the issues that had been publicly aired by Mr. Lutsenko and Mr. Giuliani.”

May 16: Lutsenko says there is no evidence of any wrongdoing by the Bidens.

May 19: In an interview with Fox News, Trump explicitly references Biden’s efforts in Ukraine.

“Biden, he calls them and says ‘Don’t you dare persecute, if you don’t fire this prosecutor’ — The prosecutor was after his son,” Trump says. “Then he said ‘If you fire the prosecutor, you’ll be okay. And if you don’t fire the prosecutor, 'we’re not giving you $2 billion in loan guarantees,’ or whatever he was supposed to give. Can you imagine if I did that?”

Again, the Burisma probe was dormant at the time, according to U.S. and Ukrainian officials, and there was no evidence it focused on any actions by the Bidens.

May 20: Zelensky is inaugurated as president of Ukraine. Shortly after the inauguration, Giuliani meets with Ukrainian officials who are allied with Lutsenko and who made allegations included in Solomon’s reporting.

May 23: The administration notifies Congress that it intends to release aid money to Ukraine.

June 13: In an interview with ABC News’s George Stephanopoulos, Trump says he might accept electoral assistance from a foreign government, if offered.

“I think you might want to listen, there isn’t anything wrong with listening,” Trump says. “If somebody called from a country, Norway, ‘We have information on your opponent'? Oh, I think I’d want to hear it.”

The chairwoman of the Federal Election Commission subsequently points out on Twitter that this would be illegal.

June 20: In an interview with Fox News, Trump links Ukraine and the effort to hack the Democratic National Committee during the 2016 election — a link that the whistleblower (and recent reporting) suggests doesn’t exist.

June 21: Giuliani tweets that Zelensky is “still silent on investigation of Ukrainian interference in 2016 election and alleged Biden bribery of Pres Poroshenko.”

July 12: Axios reports that Trump and Director of National Intelligence Daniel Coats are at odds, with Trump telling confidants that he wants to remove Coats from his position.

July 18: Trump’s decision to withhold nearly $400 million in aid to Ukraine is communicated to the State and Defense departments. Members of Congress are told that the hold is part of an “interagency delay.”

July 19: Ambassador Volker texts Giuliani to connect him with a Zelensky aide named Andrey Yermak.

Separately, Volker texts Sondland about the upcoming Zelensky call with Trump. “Most impt is for Zelensky to say that he will help investigation,” Volker says.

July 21: Bill Taylor, the U.S. charges d’affaires in Ukraine, tells Sondland via text that “President Zelenskyy is sensitive about Ukraine being taken seriously, not merely as an instrument in Washington domestic, reelection politics.”

July 22: Shokin alleges to The Post that he was removed over the Biden issue.

“I will answer that the activities of Burisma, the involvement of his son, Hunter Biden, and the [prosecutor general’s office] investigators on his tail, are the only — I emphasize, the only — motives for organizing my resignation,” he says. Other Ukrainian officials have cast doubt on this and said the investigation had long been dormant when Shokin was removed.

Yermak and Giuliani schedule a meeting in early August, according to Giuliani.

July 23. OMB reiterates that aid to Ukraine is suspended, per Trump.

July 24: Mueller testifies before Congress about his report and its findings.

July 25: Trump and Zelensky speak on the phone.

Before the call, Volker texts with Yermak and again expresses the importance of Zelensky saying he will investigate. For the first time on record, he also ties this to a potential White House meeting for Zelensky. “Heard from White House-assuming President Z convinces trump he will investigate / ‘get to the bottom of what happened’ in 2016, we will nail down date for visit to Washington,” Volker says.

On the Trump-Zelensky call, as we later find out from a rough transcript released by the White House, Trump repeatedly notes how “good” the United States is to Ukraine and then proceeds to ask Zelensky to open two investigations. One investigation involves CrowdStrike, an Internet security company that probed the Democratic National Committee hack in 2016, and the other involves the Bidens.

“I would like you to do us a favor though because our country has been through a lot and Ukraine knows a lot about it,” Trump says before floating the CrowdStrike investigation.

He later adds: “The other thing, there’s a lot of talk about Biden’s son, that Biden stopped the prosecution and a lot of people want to find out about that so whatever you can do with the Attorney General would be great. Biden went around bragging that he stopped the prosecution so if you can look into it ... It sounds horrible to me.”

Trump repeatedly suggests Attorney General Barr will be involved in working with the Ukrainian government on the investigation. Zelensky tells Trump that his yet-to-be-named new prosecutor general “will look into the situation, specifically to the company that you mentioned in this issue” — apparently referring to Burisma.

After the call, Yermak texts Volker back, saying, “Phone call went well. President Trump proposed to choose any convenient dates. President Zelenskiy chose 20,21,22 September for the White House Visit.”

The Washington Post would later report that at least four national security officials raised concerns about Trump’s Ukraine efforts with a White House lawyer both before and immediately after the Zelensky call.

Days following July 25: The whistleblower writes: “I learned from multiple U.S. officials that senior White House officials had intervened to ‘lock down’ all records of the phone call, especially the official word-for-word transcript of the call that was produced — as is customary — by the White House Situation Room. This set of actions underscored to me that White House officials understood the gravity of what had transpired in the call.”

The whistleblower claims to have been told by White House officials that they were directed by White House lawyers to move the transcript from the normal documentation archive and to “a separate electronic system that is otherwise used to store and handle classified information of an especially sensitive nature” — a move one official called an “act of abuse.”

In an appendix, the whistleblower adds that officials said “this was ‘not the first time’ under this Administration that a Presidential transcript was placed into this codeword-level system solely for the purpose of protecting politically sensitive — rather than national security sensitive — information.”

July 26: Volker and Sondland travel to Kiev and meet with Zelensky and other politicians. There, the whistleblower writes, they “reportedly provided advice to the Ukrainian leadership about how to ‘navigate’ the demands that the President had made of” Zelensky.

July 28: Trump announces that Coats will resign in August.

July 31: Trump holds a phone call with Russian President Vladimir Putin. The call is first reported by the Russians; the White House doesn’t confirm it until late that evening. The Russians, in a much more substantial readout than the United States, claim Trump and Putin spoke about restoring full diplomatic relations one day.

Aug. 2: Giuliani travels to Madrid, where he meets with a Zelensky adviser named Andriy Yermak. This meeting was a “direct follow-up” to the July 25 call, according to the whistleblower’s sources. (According to the New York Times, the meeting involves Giuliani’s encouraging Zelensky’s government to investigate Hunter Biden.) Giuliani had also been reaching out to other Zelensky advisers.

Aug. 3: Zelensky announces he will travel to the United States to meet with Trump in Washington in September.

Aug. 8: Trump announces Joseph Maguire will take Coats’s job as director of national intelligence, in an acting capacity. In doing so, he bypasses Sue Gordon, who had been Coats’s No. 2 at the directorate of national intelligence and was a career intelligence official with bipartisan support. Gordon would later resign.

Giuliani tells Fox News that the Justice Department official in charge of investigating the origins of the Russia probe is “spending a lot of time in Europe” to investigate what happened in Ukraine.

Aug. 9: Trump speaks to reporters outside the White House. He is asked about inviting Zelensky to the White House and what advice he would offer on dealing with Putin.

“I think he’s going to make a deal with President Putin, and he will be invited to the White House,” Trump says. “And we look forward to seeing him. He’s already been invited to the White House, and he wants to come. And I think he will. He’s a very reasonable guy. He wants to see peace in Ukraine. And I think he will be coming very soon, actually.”

Separately, Volker and Sondland text with one another about a statement Ukraine might be asked to issue. Sondland also indicates Trump “really wants the deliverable.” Volker and Sondland consult Giuliani about what the statement should say.

Aug. 10: Yermak emphasizes that Ukraine would like to lock down a date for Zelensky’s visit before making the statement. “I think it’s possible to make this declaration and mention all these things,” Yermak says. “Which we discussed yesterday. But it will be logic to do after we receive a confirmation of date. We inform about date of visit and about our expectations and our guarantees for future visit.”

Aug. 12: An anonymous whistleblower files a complaint with the inspector general for the intelligence community. Intelligence Community Inspector General Michael Atkinson will later determine the complaint to be credible and a matter of “urgent concern,” triggering a legally required disclosure to the House and Senate intelligence committees.

Aug. 13: Volker and Sondland text about what language should be included in Ukraine’s statement.

Aug. 15: Coats and Gordon officially leave their positions.

Aug. 17: Sondland asks Volker if “we still want Ze[lensky] to give us an unequivocal draft with 2016 and Boresma [sic]?” Volker responds, “That’s the clear message so far ...”

Late August: Lawmakers raise concerns about Ukraine aid being withheld, citing its importance to defend the former Soviet republic from Russia.

Also around this time, Sondland tells Sen. Ron Johnson (R-Wis.) that Trump was withholding the Ukraine military aid to “get to the bottom of what happened in 2016 — if President Trump has that confidence, then he’ll release the military spending," according to Johnson’s later recollection.

Aug. 29: Yermak texts Volker a link to a Politico story about the Trump administration withholding $250 million in military aid from Ukraine. (Before this point, it wasn’t clear Ukraine even knew the aid was being withheld.) “Need to talk with you,” he says, before pasting the link. Volker responds, “Hi Andrey — absolutely. When is good for you?”

Sept. 1: Taylor texts Sondland, asking, “Are we now saying that security assistance and WH meeting are conditioned on investigations?” Sondland responds, “Call me.”

Separately, Zelensky and Vice President Pence meet as various world leaders are in Poland for a ceremony commemorating World War II. Trump had originally been slated to attend the ceremony but remained in the United States to monitor Hurricane Dorian.

Sept. 2: Pence says he didn’t discuss Biden with Zelensky, but that he did suggest that aid was conditioned on rooting out corruption.

“As President Trump had me make clear, we have great concerns about issues of corruption,” Pence said. “The president wants to be assured that those resources are truly making their way to the kind of investments that will contribute to security and stability in Ukraine.”

Early September: Sen. Chris Murphy (D-Conn.) travels to Ukraine and meets with Zelensky. He later tells NBC’s Chuck Todd that Zelensky had expressed concern about Giuliani’s overtures.

Sept. 5: The Post editorial board writes that it had been “reliably told” that Trump was “attempting to force Mr. Zelensky to intervene in the 2020 U.S. presidential election by launching an investigation of the leading Democratic candidate, Joe Biden.”

Sept. 8: Taylor texts to Volker and Sondland, saying, “The nightmare is they give the interview and don’t get the security assistance. The Russians love it. (And I quit.)”

Sept. 9: Taylor texts Sondland again about the idea that the military aid is being withheld in some kind of quid pro quo. “As I said on the phone, I think it’s crazy to withhold security assistance for help with a political campaign,” Taylor says.

Sondland speaks with Trump via phone and responds to Taylor: “Bill, I believe you are incorrect about President Trump’s intentions. The President has been crystal clear no quid pro quo’s of any kind. The President is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign I suggest we stop the back and forth by text If you still have concerns I recommend you give Lisa Kenna or S a call to discuss them directly. Thanks.”

Separately, Atkinson notifies the House and Senate intelligence committees that a whistleblower has filed a complaint, but he does not reveal its contents or substance.

Sept. 10: House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) writes to Maguire demanding Congress receive the complaint.

Trump announces on Twitter that national security adviser John Bolton has resigned. Trump says it came at his request; Bolton quickly counters by saying he offered first.

Sept. 11: The Trump administration releases the Ukraine aid it had been withholding.

Sept. 13: Schiff subpoenas Maguire to compel him to disclose the whistleblower complaint.

According to Schiff, the DNI’s office, in a letter from counsel, indicates the whistleblower complaint is being withheld because of confidential and potentially privileged communications by people outside the intelligence community. It is assumed that this refers to Trump.

Sept. 17: Maguire says he will not testify or hand over the whistleblower complaint. Schiff says Maguire told him he couldn’t “because he is being instructed not to, that this involved a higher authority, someone above.”

Sept. 18: The Post reports that the complaint involves Trump’s communications with a foreign leader and some kind of “promise” that was made.

Sept. 19: Atkinson briefs Congress in a closed-door session, telling them the complaint involved multiple events and not a single communication. The Post reports the complaint involves Ukraine.

That evening, Giuliani appears on CNN and denies any wrongdoing by Trump. But he also suggests it would be okay if Trump withheld aid in exchange for Ukraine investigating the Bidens.

“The reality is the president of the United States has every right to say to another leader of a foreign country, ‘You got to straighten up before we give you a lot of money,’ ” Giuliani said. “It is perfectly appropriate for [Trump] to ask a foreign government to investigate this massive crime that was made by a former vice president.”

Sept. 23: Trump suggests aid to Ukraine may have been withheld over “corruption” issues — without citing the Bidens.

“If you don’t talk about corruption, why would you give money to a country that you think is corrupt?” Trump said. “… So it’s very important that, on occasion, you speak to somebody about corruption.”

Sept. 24: Trump confirms he withheld the funding but suggests it was because other European countries should pay for Ukraine’s military aid.

Trump later says he will release a transcript of his phone call with Zelensky.

Schiff says the whistleblower has expressed an interest in testifying.

House Speaker Nancy Pelosi (D-Calif.) announces her support for a formal impeachment inquiry for the first time, setting that process in motion.

Sept. 25: The White House releases a rough transcript of Trump’s July 25 call with Zelensky, including the details above.

Trump meets with Zelensky at the United Nations. Zelensky maintains he didn’t feel “pressure” to pursue investigations, and he didn’t interfere in his country’s law enforcement process. “We have an independent country and independent [prosecutor general]," he says. “I can’t push anyone. That is the answer. I didn’t call somebody or the new [prosecutor general]. I didn’t ask him. I didn’t push him.”

Sept. 26: The White House declassifies the whistleblower complaint, and Schiff releases it. The complaint focuses on Trump’s call with Zelensky but also alleges an effort to cover it up and alludes to substantial concern within the administration about Trump’s actions.

The same morning, Maguire testifies to the House Intelligence Committee that the Justice Department’s Office of Legal Counsel downgraded the inspector general’s determination that the whistleblower complaint was of “urgent concern,” which eliminated the requirement that it be shared with Congress. Democrats cry foul, noting that the complaint names Attorney General Barr — the head of the Justice Department — as being potentially involved.

Republicans respond to the complaint cautiously, with many of them noting it relies about secondhand information gathered by the intelligence official who wrote it.

Sept. 27: Volker abruptly resigns.

More than 300 former U.S. national security and foreign policy officials sign a statement supporting House Democrats’ impeachment inquiry.

Oct. 1: Secretary of State Mike Pompeo sends House Democrats a letter declaring that five State Department employees who had been summoned for depositions would not appear. Pompeo calls the inquiry “an attempt to intimidate, bully, and treat improperly, the distinguished professionals of the Department of State.”

Oct. 2: The New York Times reports — and The Post confirms — that the whistleblower had approached a staffer for Schiff’s committee early in the process, contradicting some of Schiff’s claims.

State Department Inspector General Steve Linick shares with Congress documents that had been sent to State Department that including conspiracy theories about the Bidens. Giuliani indicates he we responsible for some of the materials, which were apparently sent to State from the White House.

Oct. 3: Volker submits to a deposition, sharing text messages (as described above) with Taylor, Sondland, Giuliani and Yermak.

Trump says in an availability with reporters that he also thinks China should launch an investigation involving the Bidens. “And by the way, likewise, China should start an investigation into the Bidens because what happened in China is just about as bad as what happened with Ukraine,” he says.

The State Department informs Congress that it has approved the sale of 150 Javelin antitank missiles to Ukraine — a type of weaponry Zelensky mentioned on the July 25 call with Trump — at a cost of $39.2 million.

Oct. 6: Lawyers for the whistleblower indicate they are representing a second whistleblower — this one with firsthand knowledge of some of the key events. They say the second whistleblower has spoken with Atkinson.

Oct. 8: After blocking Sondland’s testimony, White House counsel Pat Cipollone informs Congress that the White House will not cooperate with its impeachment inquiry, making curious arguments about the lack of “due process.”

Oct. 10: Giuliani’s two Soviet-born business associates, Parnas and Fruman, are arrested while trying to leave the country. They are indicted on campaign finance charges, with the Southern District of New York accusing them of funneling foreign money into U.S. politics to influence U.S.-Ukraine relations.

Oct. 11: Yovanovitch testifies to Congress, alleging a politicized effort to remove her as ambassador to Ukraine.

Oct. 12: The Washington Post reports Sondland will tell Congress that his Sept. 9 text message stating there was no quid pro quo between Trump and Ukraine was based on assurances from Trump and that he is not certain Trump’s denial was accurate. Trump and his allies had hailed Sondland’s text as proof there was no quid pro quo.

Oct. 14: The White House’s former top Russia expert, Fiona Hill, testifies to Congress.