Senate Republicans will move quickly to acquit President Donald Trump — holding a vote as early as Friday — if the Senate does not vote to allow further witness testimony.

Republican Senator John Barrasso (R-WY) told reporters on Thursday that “it was possible the trial could end on Friday without Democrats achieving their goal of having witnesses called to testify,” according to Reuters.

“The momentum is clearly in the direction of moving to final judgment on Friday. That vote will be Friday,” Barrasso said. “We still have a couple members who said they want to listen to the answers to questions, but that’s where the momentum is.”

Sen. Lindsey Graham (R-SC) told Fox News that he expects that “the president will be acquitted, and I think it will be this week.”

The Senate will spend Thursday posing questions to the two sets of legal teams, the president’s slate of attorneys and the House “impeachment managers,” including Rep. Adam Schiff (D-CA). After the question and answer period has concluded, the Senate will likely adjourn until Friday morning.

As promised when the president’s Senate trial began, Senators will have one final opportunity to opt to hear from witnesses like former national security advisor John Bolton and acting White House chief of staff Mick Mulvaney. They will hold discussion on the possibility and, likely, a vote, sometime Friday morning.

Sen. Chuck Schumer (D-NY) has been pushing for witness testimony since before Trump’s Senate impeachment trial began, in the hopes that the Senate can help close holes left in the House impeachment panel’s case against the president.

First, they tried to withhold the articles of impeachment as leverage — a strategy that fell flat when Senate Majority Leader Mitch McConnell said, simply, that he would not hold a Senate trial until the articles were delivered. They then tried to convince Republicans that witnesses were necessary, a strategy that looked like it would fail, as well, until last Sunday, when early drafts of Bolton’s book leaked to the New York Times, including a passage that seemed to indicate that Trump had, indeed, withheld foreign aid from the Ukraine until Ukrainian officials agreed to pursue an investigation into former Vice President Joe Biden and his son, Hunter.

On Monday, Republican Sen. Mitt Romney (R-UT) appeared to be whipping his own small coalition of Republicans to vote for witness testimony — an effort that looked likely to succeed until sometime late Tuesday, after a “secret meeting” where McConnell and allies reportedly convinced Republicans “on the fence” about witnesses to vote against prolonging the trial.

The final vote on witnesses will likely happen Friday. Democrats need four Republicans to vote with them to press the issue as a whole. If that vote goes Democrats’ way, each witness must be assessed and then voted on, independently, before he or she is allowed to testify. Democrats would need four Republicans to vote with their caucus on each individual witness they intend to call.

If the vote does not go Democrats’ way, it’s not clear how soon the trial could conclude. The Senate rules says, simply that “[a]t the conclusion of the deliberations by the Senate, the Senate shall vote on each article of impeachment.”

“Both sides could try to make motions after the failed witness vote,” recalled the Hill. “In former President Clinton’s impeachment trial, there were two procedural votes, including a failed effort to suspend the rules, before the two votes on the articles of impeachment.” Clinton’s trial concluded on the 9th of February and a vote to acquit was held three days later, on the 12th.