It would take a two-thirds majority to convict, meaning 17 Republicans would need to join the Senate's 50 Democrats
The US Senate was expected to deliver a verdict in Donald Trump's impeachment trial this weekend after his lawyers argued on Friday that the former president bears no responsibility for an attack by supporters on Congress after he failed to win re-election.
Defence lawyers wrapped up their presentation in just three hours, accusing Democrats of persecuting Trump.
This followed two days of evidence from Democratic impeachment managers, centred around harrowing video footage of the mob assault against the Capitol on January 6.
The Senate was due to reconvene on Saturday at 1500 GMT for debate on whether to allow witness testimony, then closing arguments. Expectations were that a verdict could be voted the same day, with indications so far that Democrats will not get enough Republican support for a conviction.
In their arguments on Friday, defence lawyer Michael van der Veen called the impeachment unconstitutional and an "act of political vengeance."
"The Senate should promptly and decisively vote to reject it," he said.
But Democratic impeachment managers charge that Trump deliberately stoked national tension after losing to Joe Biden on November 3 with a campaign of lies claiming there had been mass voter fraud.
On January 6 he staged a fiery rally near the White House, calling on the crowd to march on Congress, which was in the process of certifying Biden's victory.
The mob then charged the Capitol building, disrupting the certification. Five people, including a police officer and a woman shot during the unrest, died as a result of the mayhem.
Impeachment managers say Trump, who has never expressed remorse for his encouragement of the violent crowd, is so dangerous that he should be barred from holding office again.
It would take a two-thirds majority to convict, meaning 17 Republicans would need to join the Senate's 50 Democrats.
Although Trump looks set for acquittal, even a few Republican votes against him would leave a historic mark on his presidency, fuelling civil war within his party over whether to pursue his populist, divisive vision or return to more moderate values.
'Hypocrisy' from Trump's accusers
The former president's lawyers argued that his rally speech on January 6, when he told supporters to "fight," was merely rhetorical.
They also argue that the Democrats' true aim is to remove him from the political scene.
"Let us be clear: this trial is about far more than president Trump," defence lawyer Bruce Castor said.
"It is about cancelling 75 million Trump voters, and criminalizing political viewpoints. That is what this trial is really about."
Seeking to turn the table on the Democrats' powerful use of video evidence, defence lawyers played their own compilations showing Democratic lawmakers at different times using the word "fight."
Democratic senators, along with Biden and Vice President Kamala Harris were among those shown using the word in past speeches and on television.
"Please, stop the hypocrisy," Trump's lawyer David Schoen said.
Trump 'inflamed' and 'incited'
The video footage at the heart of the impeachment managers' case showed the crowd in the Capitol on January 6 hunting down opponents of Trump as senior figures, including then vice president Mike Pence, fled for safety.
Schoen mocked the video as "an entertainment package" and said Trump could not possibly be held responsible for the actions of the demonstrators.
But lead impeachment manager Jamie Raskin pointed out that the Republican leader had been encouraging extremism even in the lead-up to Election Day by constantly undermining public faith in the election process.
"This pro-Trump insurrection did not spring out of thin air," Raskin said. "This was not the first time Donald Trump had inflamed and incited a mob."
He said it was imperative the Senate convict Trump and bar him from running for the White House again in 2024 or face the risk of the same kind of behaviour being repeated.
"Would you bet the future of your democracy on that?"
Earlier, Biden told reporters at the White House that he was "anxious to see what my Republican friends do, if they stand up," when it comes to the verdict.
There was little sign of an impending breakdown in the Trump firewall, but the verdict will make many in the party uncomfortable whichever way it goes.
Republican Senator Bill Cassidy of Louisiana said evidence shown by House managers was "powerful," but reporters spotted a draft statement from him on Friday that indicated he would be voting for acquittal.
Other Republican senators have clearly already made up their minds and do not intend to break with Trump, who has threatened to derail their careers should they back impeachment.
"The 'Not Guilty' vote is growing," tweeted Republican Senator Lindsey Graham of South Carolina.
Republican Senator Josh Hawley of Missouri told Fox News the trial was "totally illegitimate."