Senate Republicans are planning for four hours of closing arguments in President Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE’s impeachment trial starting Friday afternoon.

The arguments, presented by both the House managers and Trump's defense team, would be followed by a vote on whether to call additional witnesses and then a final up-or-down vote on the two articles of impeachment.

Republicans are aiming to wrap up the trial proceedings late Friday evening or early Saturday morning, depending on how long Democrats drag out the final vote by offering amendments to the motion to move to a final vote, said Senate Republican Conference Chairman John Barrasso John Anthony BarrassoMurkowski: Supreme Court nominee should not be taken up before election Battle lines drawn on precedent in Supreme Court fight Sunday shows - Ruth Bader Ginsburg's death dominates MORE (Wyo.).

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Under the organizing resolution adopted by the Senate last week, House impeachment managers and Trump’s defense team will each have two hours. Previous impeachment trials have allocated four hours for closing arguments.

“My understanding is essentially the closing arguments are going to be two hours for each side tomorrow afternoon, probably starting at 1 o’clock, until we’re finished with that. Then the vote would occur on the issue of witnesses,” Barrasso said at a brief press conference Thursday during a 20-minute break in the trial.

“If we are able to say, ‘No, we want to go right now to final judgment,’ then we would move in that direction and stay here until that work is decided and completed Friday evening,” he added.

Senate Republicans say they’re confident they will be able to defeat a motion to consider and debate motions for subpoenas of additional witnesses and documents.

If the motion fails on a largely party-line vote, as expected, then it will not be in order to consider subpoenas of former national security adviser John Bolton John BoltonDiplomacy with China is good for America The Hill's Morning Report - Sponsored by The Air Line Pilots Association - Pence lauds Harris as 'experienced debater'; Trump, Biden diverge over debate prep DOJ launches probe into Bolton book for possible classified information disclosures MORE, acting White House chief of staff Mick Mulvaney Mick MulvaneyMick Mulvaney to start hedge fund Fauci says positive White House task force reports don't always match what he hears on the ground Bottom line MORE, and other witnesses demanded by Democrats.

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Asked if Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellOcasio-Cortez to voters: Tell McConnell 'he is playing with fire' with Ginsburg's seat McConnell locks down key GOP votes in Supreme Court fight Video shows NYC subway station renamed after Ruth Bader Ginsburg MORE (R-Ky.) will move immediately to an up-or-down vote on the articles of impeachment if a motion to allow additional debate and consideration of subpoenas fails, as is expected, Barrasso said, “That’s where all the momentum is right now.”

Barrasso, however, said that Senate Minority Leader Charles Schumer Chuck SchumerRepublican senator says plans to confirm justice before election 'completely consistent with the precedent' Video of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral Graham signals support for confirming a Supreme Court nominee this year MORE (D-N.Y.) could delay the final up-or-down vote by offering amendments to the motion.

He said GOP senators are committed to stay in session to table Schumer’s motion until a final vote on the articles of impeachment.

“There may be a motion that Sen. Schumer can offer amendments just like he did that first day when he introduced like 11 amendments,” Barrasso said, referring to Democrats’ effort to prolong the consideration of the organizing resolution that the Senate eventually adopted at 2 a.m. on Jan. 22.

“At some point, the Democrats will realize their motions will be defeated,” he said.

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A senior Democratic aide said McConnell will likely have to advance a resolution to set the roadmap for the end of the trial akin to the organizing resolution that set up phase one.

One Democratic senator familiar with internal discussions said Schumer will not allow the final up-or-down vote to take place without a drawn-out floor fight.

“We’re thinking about those options, whether we can change the rule, what kind of motions we’re going to make. We’re are not going quietly into that good night,” the lawmaker said.

Democrats offered 11 amendments to the organizing resolution that were defeated on party-line votes. Republicans suffered only one defection when Sen. Susan Collins Susan Margaret CollinsMcConnell locks down key GOP votes in Supreme Court fight Most Americans think winner of election should pick next Supreme Court justice: poll Murkowski: Supreme Court nominee should not be taken up before election MORE (R-Maine) voted to give the parties more time to respond to each other’s briefs.

A growing number of senators on both sides of the aisle are expecting the trial to be finished by late Friday night or early Saturday morning.

Some senators have already booked plane tickets out of Washington for Saturday morning, according to a senator familiar with colleagues' travel plans.