WASHINGTON (AP) - The Senate is considering pushing off final acquittal in President Donald Trump's impeachment trial until next week under a proposal being negotiated Friday by party leaders.

The situation remained fluid, but senators have indicated they want more time to publicly debate the charges and air their positions on the coming vote, according to a Republican familiar with the proposal but unauthorized to discuss it. The person was granted anonymity.

The shift in timing ahead of Trump's all but certain acquittal shows the significance of the moment to senators in voting that would bring to a close the third presidential impeachment trial in American history.

Senate Majority Leader Mitch McConnell made the offer to Democratic Leader Chuck Schumer, the person said. Senators were considering it while the proceedings were underway on the Senate floor. Schumer had not yet agreed to it.

Trump still appeared headed for acquittal as senators prepared on Friday to reject efforts to call more witnesses and moved to start bringing the trial to a close.

Under the proposal, the vote on witnesses would still occur late Friday. But the Senate would resume Monday for final arguments, with time Monday and Tuesday for senators to speak. The final voting would be Wednesday.

The impeachment of the president is playing out in an election year before a divided nation. Democratic caucus voting begins Monday in Iowa, and Trump gives his State of the Union address the next night.

Eager for a conclusion, the president and his allies in the Republican majority are brushing past new revelations from John Bolton, Trump's former national security adviser, as well as historic norms that could make this the first Senate impeachment trial without witnesses.

In an unpublished manuscript, Bolton writes that the president asked him during an Oval Office meeting in early May to bolster his effort to get Ukraine to investigate Democrats, according to a person who read the passage and told The Associated Press. The person, who was not authorized to disclose contents of the book, spoke only on condition of anonymity.

In the meeting, Bolton said the president asked him to call new Ukrainian President Volodymyr Zelenskiy and persuade him to meet with Trump's personal lawyer, Rudy Giuliani, who was planning to go to Ukraine to coax the Ukrainians to investigate the president's political rivals. Bolton writes that he never made the call to Zelenskiy after the meeting, which included acting chief of staff Mick Mulvaney and White House Counsel Pat Cipollone. The revelation adds more detail to allegations of when and how Trump first sought to influence Ukraine to aid investigations of his rivals.

The story was first reported Friday by The New York Times.

Trump issued a quick denial.

"I never instructed John Bolton to set up a meeting for Rudy Giuliani, one of the greatest corruption fighters in America and by far the greatest mayor in the history of NYC, to meet with President Zelenskiy," Trump said. “That meeting never happened.”

At the trial, Democrats contended that without witnesses the final outcome wouldn't be a true acquittal for Trump but a cover-up.

“Is this a fair trial?” asked Rep. Val Demings, D-Fla., a House impeachment manager. “These proceedings will be a trial in name only."

Some senators pointed to the importance of the moment.

“What do you want your place in history to be?” asked one of the House managers, Rep. Jason Crow, D-Colo., a former Army Ranger.

Republicans warned that the House had already heard from 17 witnesses and presented its 28,578-page report to the Senate. The House impeached Trump largely along party lines after less than thee months of formal proceedings making it the quickest, most partisan presidential impeachment in U.S. history, they said. The trial has gone for two weeks, and they argued against prolonging it.

Trump was impeached by the House last month on two charges, first that he abused his power like no other president, jeopardizing Ukraine and U.S.-Ukraine relations. Democrats say Trump asked the vulnerable ally to investigate Joe Biden and debunked theories of 2016 election interference, withholding American security aid to the country as it battled Russia at its border. The second article of impeachment says Trump then obstructed the House probe in a way that threatened the nation's three-branch system of checks and balances.

Despite the Democrats' singular, sometimes-passionate focus on calling witnesses, the numbers are now falling short. It would take four Republicans to break with the 53-seat majority and join with all Democrats to demand more testimony.

GOP Sen. Lamar Alexander of Tennessee, said the Democrats had proved their case, that Trump abused power and obstructed Congress, but he did not think Trump's actions rose to the impeachable level.

"I didn't need any more evidence because I thought it was proved that the president did what he was charged with doing," Alexander told reporters. “But that didn't rise to the level of an impeachable offense.”

Republican Sen. Lisa Murkowski of Alaska said she, too, would oppose more testimony, having "come to the conclusion that there will be no fair trial in the Senate.'' She said, "The Congress has failed.”

Chief Justice John Roberts, in the rare role presiding over the impeachment trial, could break a tie, but that seems unlikely.

Murkowski noted in announcing her decision that she did not want to drag the chief justice into the partisan fray.

Sen. Susan Collins of Maine said late Thursday she would vote to allow witnesses in the impeachment trial, briefly raising Democrats' hopes for a breakthrough.

Protesters stood outside the Capitol as senators arrived on Friday, but few visitors have been watching from the Senate galleries.

Bolton's forthcoming book contends he personally heard Trump say he wanted military aid withheld from Ukraine until it agreed to investigate the Bidens. Trump denies saying such a thing.

The White House has blocked its officials from testifying in the proceedings and objected that there are “significant amounts of classified information" in Bolton's manuscript. Bolton resigned last September - Trump says he was fired - and he and his attorney have insisted the book does not contain any classified information.

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Associated Press writers Alan Fram, Andrew Taylor, Matthew Daly, Laurie Kellman, Deb Riechmann and Padmananda Rama contributed to this report.

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