Here's what you need to know as Sen. Robert Menendez (D-N.J.)'s corruption trial gets underway on Sept. 6. (Amber Phillips,Sarah Parnass/The Washington Post)

On Wednesday, a U.S. senator will sit before a jury of his peers and face charges that his friend bribed him to settle disputes for the government.

Both Sen. Robert Menendez (D-N.J.) and wealthy eye doctor Salomon Melgen, also on trial Wednesday, have both denied the allegations.

It's a classic corruption case with a modern political twist: If Menendez is found guilty and subsequently steps down from his position, New Jersey Gov. Chris Christie (R) could name a Republican in his place. And in a divided Senate, one extra Republican vote could make a world of difference for President Trump's agenda. Obamacare would probably have been repealed in July if Senate Republicans had an extra vote.

“The politics of it are fascinating, and they are fascinating from start to finish,” said Brigid Harrison, a political science professor at Montclair State University.

Here's a timeline of the major events in the case, and how a guilty verdict could reverberate in Washington.

2006: Menendez is elected to the Senate.

As soon as 2006: Menendez takes weekend and week-long vacations to the Dominican Republic, Florida and Paris with Melgen, on the doctor's private jet, prosecutors would later allege.

2012: Menendez gets reelected. Melgen is a major donor, contributing some $600,000 to super PACS to help his reelection campaign.

2012: An anonymous tipster reaches out to media outlets and the FBI to claim Menendez was paying for underage prostitutes while in the Dominican Republic. Those allegations didn't pan out, but they spurred the government's closer look at Menendez's relationship with Melgen, The Post's Paul Kane and Carol Leonnig reported.


Sen. Bob Menendez (D-N.J.) (AP)

April 1, 2015: Menendez is indicted on federal corruption charges. It is the first time in a generation that a sitting U.S. senator is indicted by the administration of his own party.

The Justice Department accuses Menendez of using his official position to help Melgen get around U.S. government roadblocks for his business and personal ventures. Melgen is also indicted.

The indictment alleges the men engaged in a quid pro quo since Menendez was first elected, detailing:

  • Menendez took 19 free rides on Melgen's private jets to luxury resorts around the world, sometimes bringing guests.
  • Menendez helped three of Melgen's foreign-born girlfriends get visas to visit the United States.
  • Over a period of four years, Menendez held several meetings with U.S. health officials to help Melgen settle an $8.9 million Medicare payment dispute, at one point asking then-Senate majority leader Harry M. Reid (D-Nev.) to help out.
  • Melgen made more than $600,000 in campaign donations to super PACs to get Menendez reelected in 2012.
  • As Melgen was emailing Menendez's staff in April and May 2012, promising to donate to Menendez's campaign, prosecutors allege Menendez reached out to top State Department officials to urge them to enforce a port-security contract with the Dominican Republic that would benefit Melgen's company.

Both men deny the charges. Menendez has explained that he and Melgen are old friends; they've attended children's weddings and given each other birthday gifts, and they've vacationed together. He said he was treating Melgen like any other constituent in need.

“I’m angry and ready to fight,” Menendez tells his supporters the night of the indictment.

During a news conference, March 6, 2015, Sen. Robert Menendez (D-N.J.) said he had no intention of resigning during the trial phase of the corruption investigation against him. (Reuters)

April 2015: Menendez temporarily steps down from his position as the top-ranking Democrat on the foreign relations committee as he fights the charges.

His supporters immediately zero in on the benefit Menendez's resignation could have for Obama: As a Cuban-American, Menendez vociferously opposed Obama's olive branch to Cuba.

There's no proof the indictment was in any way connected to politics. But its effect was tangible in the political world nonetheless: “The net result of the indictment was ... that a legislative check was removed from the Obama administration's foreign policy,” Harrison said. “It raises the frightening idea about the politicization of the Department of Justice.”

In the days before the trial, Obama-era officials are defending the indictment. Here's Obama's ethics chief, on Thursday:

June 2016: The Supreme Court unanimously overturns a public corruption conviction of former Virginia governor Robert F. McDonnell. McDonnell and his wife, Maureen, were convicted in 2014 for accepting luxury gifts and cash from a businessman in exchange for McDonnell using the office of governor to help the businessman.

The justices took issue with what constitutes an “official act,” arguing in McDonnell's case, it was overly broad.

Menendez's lawyers perk up at this. The senator is accused of trying to influence executive decisions, not of writing laws that helped his buddy, they plan to argue, and they will ask the judge to throw the charges out altogether.

“There is a very real chance this case might be dismissed,” as soon as it gets started, Harrison said.

April 2017: In a separate criminal case, a Florida jury finds Melgen guilty of stealing up to $105 million from Medicare by falsely reporting how much he treated patients in his Palm Beach County practice. It's one of the largest Medicare health-care fraud schemes in history. He could face 20 years in prison when he's sentenced this fall.

Those are all the key events leading up to the trial. Here's what could happen afterward:

November 2017: Roughly the time the trial is expected to finish. This is also when New Jersey will vote for a new governor and its entire legislature is up for reelection. Democrats control both chambers and are looking to use Christie's historic unpopularity (15 percent approval rating) to gain total control of the state.

Jan. 16, 2018: Christie's last day in office. This date is important if Menendez is convicted and if Menendez resigns or the Senate votes to kick him out.

The governor can choose who temporarily replaces Menendez until an election is held.

Christie would likely choose a Republican to replace a Democrat, giving Senate Republicans 53 votes, which is a magic number. If they had 53 votes in July, the Obamacare repeal bill that failed by one vote would have likely passed the Senate. If they had 53 votes in February, Vice President Pence wouldn't have had to come down to break a tie vote for Education Secretary Betsy DeVos.

In short, one extra vote in the Senate matters. A lot.

Unknown date: IF Menendez is convicted, and IF he refuses to resign, would the Senate vote to kick Menendez out? That would require two-thirds of the Senate, or 67 out of 100 senators. That means at least 15 Democrats would have to join all Republicans. Harrison is doubtful, given how much goodwill Menendez has built up — and how one vote can hold the line for Democrats these days.

November 2018: Menendez's seat is up for grabs. Especially if Menendez is found not guilty, “the expectation is he would run again and win,” Harrison said. It certainly wouldn't be the first time New Jersey voters voted for a politician accused of corruption.

Correction: After being indicted, Menendez did not initially refuse to step down from his post as the top Democrat on the Senate Foreign Relations Committee. He chose to, according to his office.