The House voted on Wednesday to send the articles of impeachment to the Senate and appoint the Democrats’ seven-member team of managers who will prosecute President Donald Trump’s impeachment trial.

The vote, which was largely along party lines, comes after Speaker Nancy Pelosi delayed transmitting the articles for nearly a month as she sought to pressure Senate Republicans to call in new witnesses against Trump.

The articles of impeachment will be sent across the Capitol in a formal procession on Wednesday afternoon, with the Senate’s swearing-in to begin Thursday. Although Chief Justice John Roberts is expected in the Capitol Thursday to swear in senators, the trial won’t really get underway until next week after Congress returns following the Martin Luther King Jr. holiday.

“We are here today to cross a very important threshold in American history,” Pelosi said in floor remarks just before the vote. Rep. Collin Peterson (D-Minn.) was the lone Democratic “no” vote.

In her floor speech, the speaker noted how she resisted for months moving forward with impeachment despite building pressure within her caucus, declaring Trump “wasn’t worth it.”

But once the Ukraine scandal surfaced, in which Trump allegedly tried to aid his reelection campaign by pressuring the country’s president to investigate Joe Biden, Pelosi said she could no longer resist moving ahead.

“He crossed a threshold. He gave us no choice,” Pelosi said of Trump.

The House voted to impeach Trump on Dec. 18, charging him with abuse of power and obstruction of Congress for using his office and government resources to pressure Ukraine and then stonewalling the House’s efforts to investigate the scandal.

The GOP-controlled Senate is expected to acquit Trump, but as Pelosi has repeatedly noted, his presidency will forever be accompanied with the asterisk of impeachment. Trump is only the third president in history to be impeached.

“And yes it is a fact – when someone is impeached, they are always impeached. It is true, once someone is impeached it cannot be erased,” Pelosi said Wednesday.

Earlier in the day, Pelosi appointed a team of seven House Democrats to serve as prosecutors, led by her close ally House Intelligence Committee Chairman Adam Schiff (D-Calif.).

In addition to Schiff, Pelosi named House Judiciary Committee Chairman Jerry Nadler (D-N.Y.), Zoe Lofgren (D-Calif.), Hakeem Jeffries (D-N.Y.), Jason Crow (D-Colo.), Val Demings (D-Fla.) and Sylvia Garcia (D-Texas) as managers.

“What is at stake here is the Constitution of the United States. This is what an impeachment is about,” Pelosi said, flanked by her new managers, whose names had remained strictly secret even to other members of Democratic leadership until just before the announcement.

As early as Thursday morning, the managers will read the resolution — as well as the full articles of impeachment — on the Senate floor. Senators are expected to be sworn as early as Thursday afternoon by Roberts. But the trial won’t begin in earnest until Tuesday, according to Senate Majority Leader Mitch McConnell.

Under the rules of the Senate, Trump is summoned and given a time to respond. And during the trial, senators are expected to be in the chamber for all proceedings and are largely prohibited from talking, even having to write down questions they would like to ask.

Pelosi made clear she hand-picked the Democrats who will present the strongest possible case against Trump — both substantively and procedurally — to the Senate. Leading the team will be Schiff, who was one of the main public faces of impeachment over the last four months.

“The emphasis is on litigators. The emphasis is on comfort level in the courtroom,” Pelosi said, explaining the team she assembled. “The emphasis is on making the strongest case to protect our Constitution.”

Schiff, a former prosecutor turned House Intelligence Committee chairman, has earned the trust from across the caucus as he argued the public case against Trump for his role in the Ukraine scandal in a slate of public hearings this fall.

Every one of the impeachment managers has a background in practicing law or law enforcement. All but one — Crow — served on the committees leading the investigations into Trump, hearing dozens of hours of closed-door depositions that ultimately resulted in the president’s impeachment in December.

The group could hardly look more different from the 13 white men who prosecuted former President Bill Clinton in 1999. Pelosi’s team includes three women and four men, as well as two members of the Congressional Black Caucus and a member of the Congressional Hispanic Caucus.

Pelosi made a concerted effort to tap Democrats who don’t come from the traditional liberal power centers: Crow is from Colorado. Garcia is from Texas and Demings is from Florida. Still, more than half of the group hails from New York or California.

Top House Democrats will formally march the articles of impeachment over to the Senate later Wednesday afternoon. It’s an arcane tradition that has been held up since the impeachment vote in mid-December as Pelosi sought to extract concessions from Senate Republicans on the particulars of the trial.

Pelosi and her prosecution team used the Wednesday press conference to make a final plea to the Senate to bring in new witnesses and unearth new documents that hadn’t been available to the House trial.

“The American people deserve a fair trial, our democracy deserves a fair trial, our constitution deserves a fair trial,” Jeffries said at the press briefing. “Speaker Pelosi has given us the space for the American people to weigh in over the last few weeks.”

Yet Senate Majority Whip John Thune (R-S.D.) warned Democrats that Trump’s defense team will also seek witnesses to testify.

“If the Democrats decide they want to subpoena or call John Bolton or [Mike] Pompeo or [Mick] Mulvaney or whoever that is, then the president’s counsel is going to want to call its list of witnesses too,” he said Wednesday.

Pelosi, however, maintained that senators should focus on Trump’s offenses.

“The president violated his oath of office, undermined our national security, jeopardized the integrity of our elections, tried to use the appropriations process as his personal ATM machine,” Pelosi said. “That is what the senators should be looking into.”

Burgess Everett contributed to this story.