House Speaker Nancy Pelosi, D-Calif., speaks during a news conference Wednesday to announce the impeachment managers. From the left are Rep. Sylvia Garcia, D-Texas; Rep. Jerrold Nadler, D-N.Y.; Rep. Adam Schiff, D-Calif.; Rep. Val Demings, D-Fla.; and Rep. Zoe Lofgren, D-Calif. J. Scott Applewhite/Associated Press

WASHINGTON — The managers chosen to prosecute the impeachment case against President Trump will make their case to all 100 senators. But to get the trial they want, they need just four Republicans.

The House Democrats presenting the case at trial face the unique challenge of persuading a handful of senators to cross the aisle and join Democrats in demanding that the trial include documents and witnesses most Republicans would like to avoid.

In a polarized era, even that modest goal could prove difficult. But it is Democrats’ only hope to avoid the abrupt acquittal Trump is seeking. How that phase plays out could shape the depth of the stain of impeachment on Trump’s legacy, and the fortunes of many of the senators who will be on the ballot in November along with the president.

Senate Majority Leader Mitch McConnell has signaled skepticism about hearing from witnesses, though he hasn’t ruled it out. And many in his caucus have said they want to stay within the confines of the case the House has sent over. They say that if the House wanted more information, they should have gone to court for it.

However, “fifty-one senators will decide who to call,” McConnell acknowledged Tuesday.

There are already signs that the House push – and House Speaker Nancy Pelosi’s four-week delay in sending the articles – is having the desired effect.

Sen. Susan Collins of Maine, a moderate Republican who is seeking re-election this year, has negotiated with McConnell to ensure there will be a vote after opening arguments on whether to call witnesses.

But Collins made it clear she wants the process to be fair to both sides.

“The idea that only the House managers should be able to call witnesses is one I reject,” The Washington Post quoted her as saying. “It clearly should be both sides, both sides should have the opportunity. But as far as approving specific witnesses, I haven’t heard the case yet.”

Collins added: “I don’t know which witnesses we’re going to need until I hear the case.”

The House impeached Trump Dec. 18 for abuse of power and obstruction of Congress after an investigation into the president’s pressure on Ukraine to investigate Democrats. Those articles will be formally presented to the Senate on Thursday, triggering a trial.

Pelosi hand-selected the seven House members who will make the case for Trump’s conviction and removal from office. She said their focus would be on “making the strongest possible case to protect and defend our Constitution, to seek the truth for the American people.”

While the Democratic prosecutors can look to former President Bill Clinton’s impeachment for a model, their challenge is different. In Clinton’s trial, the 13 GOP managers already had an exhaustive trail of evidence, delivered by independent counsel Kenneth Starr.

For Trump, the House had to compile its own case, using a whistle-blower complaint as a guide. But lawmakers were unable to obtain testimony and documents from key administration officials who refused to cooperate, under orders from the White House.

Former National Security Adviser John Bolton, for example, has said he will testify before the Senate but refused to talk to the House. Bolton was present for many of the key episodes in which Trump pressured Ukraine as he ordered military aid to the country withheld.

If the Democrats can obtain new information during the trial from Bolton and other witnesses, it could extend the proceedings and prevent a rapid acquittal. But with only 47 Democrats in the Senate, they’ll need support from at least four Republicans to obtain the necessary 51 votes – and there’s no guarantee they’ll get there.

The task of convincing them falls primarily to House Intelligence Committee Chairman Adam Schiff and House Judiciary Committee Chairman Jerrold Nadler, whose committee wrote and approved the two articles of impeachment.

California Rep. Zoe Lofgren, who is working on her third presidential impeachment, is another manager who will make the case. She’ll be joined by two freshmen, Colorado Rep. Jason Crow and Texas Rep. Sylvia Garcia, who were a litigator and a judge, respectively, before coming to Congress.

Rounding out the group is New York Rep. Hakeem Jeffries, the chairman of the House Democratic Conference, and Florida Rep. Val Demings, a former chief of the Orlando Police Department.

“The emphasis is on litigators,” Pelosi said at a morning press conference. “The emphasis is on comfort level in the courtroom.”

Schiff said the managers intend to lay out facts of their case in detail, using video clips from House testimony to inform not only the senators in the room, but also the millions of Americans watching the trial who could pressure Republicans to act.

Democrats are trying to keep up the pressure. On Tuesday, three House committees released documents provided by an associate of Trump’s personal lawyer, Rudy Giuliani. The documents from Lev Parnas detail his work as an intermediary in Ukraine as Trump pushed the investigations of Joe Biden and the Democrats.

Schiff said he expects more evidence to come out as the trial progresses.

“One thing that senators are going to have to think about is, if they prohibit us from getting the documents, they’re going to come out over time anyway,” Schiff said. “And it will be very difficult for them to explain to the country why they voted not to see the evidence at a time when it would have helped them in their judgment.”

“The challenge,” Schiff said, “is to get a fair trial.”