Senators Susan Collins R-Maine talks to reporters before attending the impeachment trial of President Donald Trump on charges of abuse of power and obstruction of Congress, Tuesday, Jan. 28, 2020, on Capitol Hill in Washington. Credit: Jose Luis Magana | AP

WASHINGTON — U.S. Sen. Susan Collins said late Thursday she will vote for calling more witnesses in President Donald Trump’s impeachment trial, but a Democratic-led bid for more testimony looked unlikely to pass as the Senate moved toward an imminent vote for acquittal.

A vote on witnesses, expected Friday, could lead to an abrupt end and assured acquittal in only the third presidential impeachment trial in American history. Trump was pressing for action in time for his State of the Union address, and that now seems likely. As the Republican-led Senate adjourned late Thursday, it set the date for Tuesday night’s speech.

Despite the Democrats’ singular, sometimes-passionate focus on witnesses after revelations from John Bolton, the former national security adviser, 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. Chief Justice John Roberts, in the rare role presiding over the impeachment trial, could break a tie, but that seems unlikely.

Before Alexander’s statement, Republican Sen. Susan Collins of Maine said in a statement late Thursday she would vote to allow witnesses in the impeachment trial, briefly raising Democrats’ hopes for a breakthrough. She has signaled such a vote all month alongside Sen. Mitt Romney, R-Utah, and pushed to have the Friday vote scheduled in early January.

“I believe hearing from certain witnesses would give each side the opportunity to more fully and fairly make their case, resolve any ambiguities, and provide additional clarity,” she said.

Minutes later, Sen. Lamar Alexander, R-Tennessee, said “there is no need for more evidence to prove something that has already been proven and that does not meet the U.S. Constitution’s high bar for an impeachable offense.” On Monday, Lisa Murkowski of Alaska, who alongside Collins and Alexander was playing an outsized role in the final hours of debate with pointed questions, said she would vote against admitting witnesses.

Trump was impeached by the House last month on charges 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, temporarily halting 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.

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.

Thursday’s testimony included soaring pleas to the senators-as-jurors who will decide Trump’s fate, to either stop a president who Democrats say has tried to cheat in the upcoming election and will again, or to shut down impeachment proceedings that Republicans insist were never more than a partisan attack.

“Let’s give the country a trial they can be proud of,” said Rep. Adam Schiff, the lead prosecutor for House Democrats. He offered to take just one week for depositions of new witnesses, sparking new discussions.

Trump attorney Eric Herschmann declared the Democrats are only prosecuting the president because they can’t beat him in 2020.

“We trust the American people to decide who should be our president,” Herschmann said. “Enough is enough. Stop all of this.”

BDN writer Michael Shepherd and Associated Press writers Alan Fram, Andrew Taylor, Matthew Daly, Laurie Kellman and Padmananda Rama contributed to this report.