President Donald Trump was set to win acquittal from impeachment on Wednesday, hours after his partisan State of the Union speech triggered unprecedented protests from Democrats in a seething display of US political divisions.
Mr Trump's exoneration on abuse of power and obstruction of Congress after a nearly three-week Senate trial is expected to come along party lines, highlighting his firm lock on Republican loyalty - and the Democrats' profound disdain.
Democratic senators were expected to spend Wednesday making last-minute arguments for his conviction ahead of a 4pm (8am AEDT Thursday) vote, but the outcome was not in doubt: conviction requires a two-thirds majority of the body, and Republicans hold 53 of the 100 seats.
Acquittal won't mean an end to Democratic-led investigations of the US leader but will give Mr Trump momentum in his bid to win re-election for another four years in the White House after a tumultuous first term.
Political war
Mr Trump's annual speech before Congress late on Tuesday was a checklist of his accomplishments, both real and imagined, laid out as a gauntlet to any of the dozen or so Democrats vying to challenge him in the November vote.
Much of the 78-minute speech was given to proclaiming his successful economic policies and extolling his "America first" outlook.
He said his policies of deregulation and tax cuts - criticised by opponents as damaging the environment and favouring the wealthy over the poor - were responsible for "unparalleled" economic success.
He listed the North American USMCA trade pact, a trade deal with China, massive military spending, "unprecedented" measures to stop illegal immigration, and his bid to "end America's wars in the Middle East" as examples of fulfilling his commitments to voters.
Meanwhile, he repeatedly condemned the achievements of his Democratic predecessor, Barack Obama, and declared that his administration alone had reversed "economic decay" and "restored" American pride.
US House of Representatives Speaker Nancy Pelosi appears to rip a copy of President Donald Trumps speech after he delivers the State of the Union address. Source: AFP
"We have shattered the mentality of American decline and we have rejected the downsizing of America's destiny," he said.
"America's enemies are on the run, America's fortunes are on the rise, and America's future is blazing bright."
'He must be removed'
The speech, and Mr Trump's snub of House Speaker Nancy Pelosi just before he began, when he refused the offer of a customary handshake, only further stirred Democratic anger.
Seconds after Mr Trump finished, Ms Pelosi, the top Democrat in Congress, ripped up her copy of the speech live on television.
That deep frustration will only be exacerbated on Wednesday afternoon in the impeachment vote.
Mr Trump was accused of freezing $391 million in defence aid to coerce Ukraine into announcing probes into the Democrats and Obama vice president Joe Biden, one of the leading contenders for the party's presidential nomination.
Democrats - backed at least in part by several Republicans who appear to have accepted the prosecution's version of the facts - say this constituted an illicit invitation for a foreign government to interfere in a US election.
"When our president invites and pressures a foreign government to smear a political opponent and corrupt the integrity of our 2020 presidential election, he must be removed from office," Democrat Jeff Merkley said on the Senate floor Wednesday.
But two weeks of arguments, marked by Republicans' refusal to subpoena witnesses and White House documents that could have supported the prosecution, did not appear to erode Mr Trump's hold on power.
His popularity rating as president hit a three-year high on the eve of the impeachment verdict at 49 per cent, according to opinion poll Gallup.
House impeachment manager Adam Schiff speaks during the impeachment trial against President Donald Trump in the Senate. Source: Senate Television
Republican Senator John Cornyn argued that the unprecedented removal from office of a US leader is not merited by the impeachment charges and evidence, which he called deeply partisan.
The issue should be settled at the ballot box in November, and not by a conviction in the Senate, Mr Cornyn said.
"Impeachment of a president of the United States is simply the gravest undertaking we can pursue in this country. It is the nuclear option of our constitution, it's the choice of last resort."
