WASHINGTON (Reuters) - Amid uncertainty over the question of whether to call witnesses in President Donald Trump’s Senate impeachment trial, his legal team wrapped up its opening arguments on Tuesday with an appeal for a quick acquittal.

Saying “it is time for this to end,” Trump’s lawyers brushed off former national security adviser John Bolton’s explosive allegations about Trump’s conduct and accused Democrats of trying to interfere with Trump’s November re-election bid.

Afterward, Republican senators met behind closed doors to discuss calling witnesses including Bolton, but said as they emerged that there was no resolution on the matter. Four Republicans would need to vote for witnesses, along with all 47 Democrats and independents.

Senate Majority Leader Mitch McConnell told senators in the meeting he did not currently have the votes to block Democrats from calling witnesses at the trial because some Republicans remained uncommitted, several media outlets reported.

Republican Senator John Barrasso told reporters the consensus in the meeting was “we’ve heard enough and it’s time to go to a final judgment vote.” But other Republicans said the vote count was unclear and no decision would be made until Friday.

Republican Senator Kevin Cramer, a conservative defender of Trump who opposes witnesses, said Republicans were “mostly united” against witnesses, but added: “I’m pretty sure it’s not unanimous. But I don’t know what the numbers are.”

Trump’s legal team sought to minimize the importance of Bolton’s unpublished book manuscript that describes Trump’s central role in a pressure campaign aimed at getting Ukraine to investigate Joe Biden, a leading contender for the Democratic nomination to face Trump in this year’s election.

“You cannot impeach a president on an unsourced allegation,” Trump’s personal lawyer Jay Sekulow told the Senate.

The Democratic-led House on Dec. 18 impeached Trump on charges of abuse of power and obstruction of Congress arising from his request that Ukraine investigate Biden, the former vice president, setting the stage for the trial to determine if he should be removed from office.

The Republican-controlled Senate is almost certain to acquit Trump, who has painted the impeachment proceedings as an effort by Democrats to poison his re-election.

“While we are creating jobs and killing terrorists, the congressional Democrats are obsessed with demented hoaxes, crazy witch hunts and deranged partisan crusades,” Trump told a rally in Wildwood, New Jersey, on Tuesday.

Trump’s legal team echoed the president’s comments.

‘SERIOUS AND LASTING DAMAGE’

“Overturning past elections and massively interfering with the upcoming one would cause serious and lasting damage to the people of the United States and to our great country. The Senate cannot allow this to happen,” White House Counsel Pat Cipollone told the Senate.

“It is time for this to end, here and now,” he said.

When senators reconvene on Wednesday, they will begin two days of questions to the lawyers representing Trump and to the seven House of Representatives Democrats who have served as prosecutors. That would leave a vote on witnesses for Friday.

Adam Schiff, who served as the lead Democratic prosecutor in arguing the case against Trump last week, told reporters: “A fair trial involves witnesses and it involves documents.”

Slideshow ( 11 images )

Bolton’s manuscript directly contradicts Trump’s account of events. He wrote that the president told him he wanted to freeze $391 million in security aid to Ukraine until Kiev pursued investigations into Democrats, including Biden and his son Hunter Biden, the New York Times reported.

Bolton’s allegations go to the heart of impeachment charges against Trump. Democrats have said Trump abused his power by using the security aid - approved by Congress to help Ukraine battle Russia-backed separatists - as leverage to get a foreign power to smear a political rival.

Sekulow underscored what fellow Trump legal team member Alan Dershowitz told senators on Monday - that even if what Bolton says is true, it would not represent impeachable conduct.

Trump has denied telling Bolton he sought to use the Ukraine aid as leverage to get Kiev to investigate the Bidens. He has denied any quid pro quo - a Latin term meaning a favor for a favor - in his dealings with Ukraine.

Slideshow ( 11 images )

Bolton left his White House post last September. Trump has said he fired Bolton. Bolton said he quit after policy disagreements.

‘NOT A GAME OF LEAKS’

Sekulow told the senators that impeachment “is not a game of leaks and unsourced manuscripts. That’s politics, unfortunately.”

Nielsen data released on Tuesday showed television viewership for the trial rose on Saturday as Trump’s legal team began laying out the case for his acquittal with an estimated 10.1 million people in the United States tuned in.

Ratings had peaked at about 11 million viewers on opening day a week ago and fell to 6.8 million on Friday as Democrats wrapped up their arguments, Nielsen said.

Some Republican senators who oppose calling witnesses proposed that Bolton’s manuscript be made available for senators to review on a classified basis, an idea rejected by top Senate Democrat Chuck Schumer.

“What an absurd proposal. It’s a book,” Schumer told reporters about the proposal floated by Republican Senators Lindsey Graham and James Lankford, saying there was no need to place the manuscript for review in a classified setting “unless you want to hide something.”

Lankford urged Bolton to speak publicly outside of the trial.

Schumer criticized Trump’s legal team for stating during its arguments to the Senate that there was no eyewitness testimony detailing abuse of power by Trump, “when we know that John Bolton has eyewitness testimony and is willing to testify.”

Schumer made a fresh appeal for four Republican senators - the number needed for a majority - to join Democrats in voting to call witnesses. Schumer also indicated Democrats would reject any effort at a so-called witness swap with Republicans.

“The Republicans can call who they want. They have the ability. They have the majority,” Schumer said.

(GRAPHIC: Impeachment of U.S. President Donald Trump - here)