The vote was 228-193, coming at the start of a presidential election year and one month after the House impeached Mr. Trump

The U.S. House voted on January 15 to send two articles of impeachment against President Donald Trump to the Senate and approve House prosecutors for only the third impeachment trial in American history.

The nearly party-line vote moved Mr. Trump’s impeachment from Speaker Nancy Pelosi’s Democratic-run House to the Republican-majority Senate, where Mr. Trump expects acquittal, even as new evidence is raising fresh questions about his Ukraine dealings.

The vote was 228-193, coming at the start of a presidential election year and one month after the House impeached Mr. Trump. The president is charged with abuse of power over his pressure on Ukraine to investigate Democratic rival Joe Biden, using military aid to the country as leverage. Mr. Trump was also charged with obstructing Congress’ ensuing probe..

"We are here today to cross a very important threshold in American history,” Ms. Pelosi said, addressing the House before the vote. Earlier, she declared: “This is what an impeachment is about. The president violated his oath of office, undermined our national security, jeopardized the integrity of our elections.”

Mr. Trump, during an event at the White House, rejected the charges as a “hoax.”

The seven-member prosecution team will be led by the chairmen of the House impeachment proceedings, Reps. Adam Schiff of the Intelligence Committee and Jerry Nadler of the Judiciary Committee, two of Ms. Pelosi’s top lieutenants for only the third presidential impeachment in the nation’s history.

Ahead of the session on Jan. 15, Mr. Schiff released new records from Lev Parnas, an associate of Mr. Trump’s lawyer Rudy Giuliani, about the Ukraine strategy. including an exchange with another man about surveilling later-fired Ambassador Maria Yovanovitch.

Mr. Schiff said the new evidence should bring more pressure on Senate Majority Leader Mitch McConnell, who is reluctant to allow witnesses to testify.

“If McConnell makes this the first trial in history without witnesses, it will be exposed for what it is and that is an effort to cover up for the president,” Mr. Schiff said.

Later on January 15, the House managers are to walk the articles across the Capitol to the Senate in a dramatic procession. The Senate trial is set to start on January 16.

Mr. McConnell opened the Senate dismissing what he called a rushed impeachment that is more about the politics of Democrats who don’t like Mr. Trump than the charges against him.

"This isn’t really about Ukraine policy or military money,” Mr. McConnell said. “This has been naked partisanship all along.”

During Pelosi’s press conference announcing managers, Mr. Trump tweeted that impeachment was “another Con Job by the Do Nothing Democrats. All of this work was supposed to be done by the House, not the Senate!”

Trump’s trial will be only the third presidential impeachment trial in U.S. history, and it comes against the backdrop of a politically divided nation in an election year.

The Senate is expected to transform into an impeachment court as early as Thursday, although significant proceedings wouldn’t begin until next Tuesday after the Martin Luther King Jr. holiday. The Constitution calls for the chief justice to preside over senators, who serve as jurors and swear an oath to deliver “impartial justice.”

The managers are a diverse group with legal, law enforcement and military courtroom experience, including Hakeem Jeffries of New York, Sylvia Garcia of Texas, Val Demings of Florida, Jason Crow of Colorado and Zoe Lofgren of California.

Mr. McConnell, who is negotiating rules for the trial proceedings, is under competing pressure from his party for more witnesses, from centrists who are siding with Democrats on the need to hear full testimony and conservatives mounting Mr. Trump’s defense.

Senate Republicans signaled they would reject the idea of simply voting to dismiss the articles of impeachment against Mr. Trump, as Mr. Trump himself has suggested. Mr. McConnell agreed he does not have the votes to do that.

Mr. McConnell said on January 14: “Our members feel we have an obligation to listen to the arguments.”

A mounting number of senators say they want to ensure the ground rules include the possibility of calling new witnesses.

Sen. Susan Collins of Maine is leading an effort among some Republicans, including Mitt Romney of Utah and Lisa Murkowski of Alaska for votes on witnesses.

Mr. Romney said he wants to hear from John Bolton, the former national security adviser at the White House, who others have said raised alarms about the alternative foreign policy toward Ukraine being run by Giuliani.

Democrats have been pushing Republicans to consider new testimony, arguing that fresh information has emerged during Pelosi’s monthlong delay in transmitting the charges.

Republicans control the chamber, 53-47, and are all but certain to acquit Mr. Trump. But it takes just 51 votes during the trial to approve rules or call witnesses. Just four GOP senators could form a majority with Democrats to insist on new testimony. It also would take only 51 senators to vote to dismiss the charges against Mr. Trump.

At the private GOP lunch on January 14, Sen. Rand Paul of Kentucky warned that if witnesses are allowed, defense witnesses could also be called. He and other Republicans want to subpoena Mr. Biden and his son, Mr. Hunter, who served on the board of a gas company in Ukraine, Burisma, while his father was vice president.

Mr. McConnell prefers to model Mr. Trump’s trial partly on the process used for President Bill Clinton’s impeachment trial in 1999. It, too, contained motions for dismissal or calling new witnesses.

Mr. McConnell is hesitant to call new witnesses who would prolong the trial and put vulnerable senators who are up for reelection in 2020 in a bind with tough choices. At the same time, he wants to give those same senators ample room to show voters they are listening.