E.U. Ambassador Gordon Sondland outlined the instructions from President Trump with something of a shrug.

“We asked the White House to arrange a working phone call from President Trump and a working Oval Office visit,” Sondland said in prepared testimony before the House Intelligence Committee on Thursday. He was describing the events of a meeting on May 23, shortly after Ukrainian President Volodymyr Zelensky was inaugurated. “However, President Trump was skeptical that Ukraine was serious about reforms and anti-corruption, and he directed those of us present at the meeting to talk to Mr. [Rudolph W.] Giuliani, his personal attorney, about his concerns. It was apparent to all of us that the key to changing the President’s mind on Ukraine was Mr. Giuliani.”

Sondland said later that “we were also disappointed by the President’s direction that we involve Mr. Giuliani” but that the group figured a Giuliani-cleared meeting was better than no meeting at all.

While there are certainly still a number of unanswered questions surrounding Trump’s efforts to get Ukraine to help undermine both former vice president Joe Biden and the investigation into Russian interference in the 2016 election, one aspect of that effort has become increasingly clear. While Trump was directly involved, he also relied heavily on Giuliani (not an administration official) and acting White House chief of staff Mick Mulvaney (whose service in that role doesn’t require Senate confirmation) to figure out how to get Ukraine to play ball.

On Thursday, Mulvaney made clear the extent to which he was involved in that push. During a news conference, he declared that the administration had withheld aid to Ukraine in part because Trump was looking for help undermining the Russia probe. He later issued a statement denying there was any quid pro quo — somewhat bafflingly — but, as The Washington Post’s Ashley Parker reports, it revealed just how central Mulvaney and Trump were to figuring out how to extract the information Trump wanted.

It looked something like this.

Over and over, Trump tasked Giuliani and Mulvaney with pressing the issue. Over and over, one of the two was identified as a driver for pressuring Ukraine. Over time, Sondland himself got more directly involved with Trump, as well. Specifically:

Trump→Giuliani. By early May, Giuliani’s centrality was already established. When news broke that he planned to travel to Ukraine to try to dig up dirt focused on the Bidens and the 2016 election interference, he told the New York Times on May 9 that the information he received to that end “will be very, very helpful to my client, and may turn out to be helpful to my government.” The benefit to Trump was the primary focus.

Trump→Giuliani→Volker, Sondland and Perry. In the May 23 meeting referred to above, Trump directed a group that took to calling itself the “three amigos” to work with Giuliani. That included Sondland, special envoy to Ukraine Kurt Volker and Energy Secretary Rick Perry, who on Thursday announced his resignation from the administration. Sondland claimed not to have been aware of Giuliani’s efforts on Biden — though, of course, the meeting came weeks after Giuliani had already spoken publicly about the issue.

Mulvaney→Sondland→Bolton and Hill. During a meeting in the White House on July 10, Sondland reportedly told a group including Perry, then-national security adviser John Bolton and Russia adviser Fiona Hill that a meeting with Zelensky would be predicated on Ukraine ginning up the investigations Trump wanted. Sondland said the condition came from Mulvaney.

Trump→Mulvaney. On July 18, Trump instructed Mulvaney to halt planned aid to Ukraine. (Coincidentally, that aid had been confirmed to Congress by the administration on May 23.) Mulvaney on Thursday said this halt was a function of three things: “the corruption in the country, whether or not other countries were participating in support of Ukraine, and whether or not they were cooperating in an ongoing investigation with our Department of Justice.” That last part is what he later said wasn’t quid pro quo. (Attorney General William P. Barr announced the launch of an investigation into the Russia investigation on May 13.)

Giuliani→Volker→Sondland; Volker→Giuliani→Yermak. The following day, July 19, Volker connected Giuliani to Zelensky aide Andrey Yermak. Volker also texted Sondland to tell him that he’d had breakfast with Giuliani and that the most important part of a call with Trump was “for Zelensky to say that he will help investigation — and address any specific personnel issues — if there are any.”

Trump→Sondland … Volker→Yermak … Zelensky; Trump→Zelensky→Giuliani and Barr. On July 25, Trump and Zelensky spoke on the phone. Trump told the Ukrainian leader that he wanted to see two investigations in particular and suggested Giuliani and Barr would aid in the probes. An aide to Vice President Pence sat in on the call.

Before the call, Trump and Sondland spoke on the phone. At about the same time, Volker texted Yermak, telling the aide that a desired Zelensky trip to Washington would be “nailed down,” “assuming President Z convinces trump he will investigate / 'get to the bottom of what happened’ in 2016.” Presumably Yermak conveyed that to Zelensky. It’s not clear if Volker’s advice stemmed from Sondland’s call with Trump.

Giuliani→Volker, Sondland. The three set up a meeting on Aug. 9 to figure out what a statement announcing Ukrainian probes could look like. Earlier, Sondland and Volker discussed how important that “deliverable” was to Trump.

Trump … Sondland→Johnson. On Aug. 29, Yermak contacted Volker to raise concerns about the halted aid. On Aug. 30, Trump canceled a planned trip to Poland, where he’d been slated to meet with Zelensky. Later that day, Sondland told Sen. Ron Johnson (R-Wis.) that the block on aid to Ukraine was tied to a 2016 investigation (as Mulvaney also said on Thursday). Johnson told reporters that Sondland said Zelensky needed to find a prosecutor who could “get to the bottom of what happened in 2016 — if President Trump has that confidence, then he’ll release the military spending.”

The next day, Trump denied quid pro quo to Johnson — but rejected Johnson’s offer to tell Zelensky the aid was released because it was being held out of concern for what allegedly happened in 2016.

Trump→Pence→Zelensky … Taylor→Sondland. Trump asked Pence to travel to Poland and meet with Zelensky on Sept. 1. Pence was instructed to tell Zelensky that aid is being withheld, a decision, Pence later told reporters, made out of concern that corruption would result in monetary aid being wasted. The same day, acting Ukraine ambassador Bill Taylor asked Sondland whether the aid was being conditioned on Trump’s desired investigations. It’s not clear whether Taylor’s question stemmed from Pence’s visit.

Trump→Sondland→Taylor. Taylor repeated his question about an aid-for-investigations mandate on Sept. 9. Sondland replied that there was no quid pro quo at play — only after speaking with Trump.

Within three weeks, the entire effort to get Ukraine to launch investigations became public.