The US Senate has found that the impeachment trial of former President Donald Trump is constitutional, allowing full proceedings to begin.
Mr Trump’s defence team argued that he cannot face trial after leaving the White House.
But a 56-44 majority voted in favour of continuing, with a handful of Republicans backing the measure.
Mr Trump is accused of “inciting insurrection” when Congress was stormed last month.
Democrats prosecuting the case opened Tuesday’s proceedings by showing a video montage of Mr Trump’s 6 January speech and the deadly rioting by some of his supporters.
“That’s a high crime and misdemeanour,” Representative Jamie Raskin of Maryland said of the footage. “If that’s not an impeachable offense, then there’s no such thing.”
Lawyers for the former president argued it was unconstitutional to put a former president through the process at all and accused Democrats of being politically motivated.
The 56-44 split means six Republicans joined Democrats in voting to go ahead with the trial.
Although this shows some bipartisanship, this result implies loyalty toward the former president in his party remains high enough to avoid a conviction.
A two-thirds majority is required to convict Mr Trump in the evenly split 100-seat Senate. The terror of being trapped in the US Capitol – three eyewitness accounts of politicians
Starting Wednesday at noon, each side will be given 16 hours to make their arguments in the case.
It is not clear how long the trial will last or if witnesses will be called, but lawmakers on both sides are said to favour a speedy trial.
Donald Trump’s Senate trial is just getting started. The final outcome, however, is all but certain.
When the first substantive vote of the proceedings was taken on Tuesday – a vote about whether to have a trial at all – only six Republicans sided with all 50 Democrats to continue.
That’s well short of the 17 Republicans that will be needed to convict.
The grim reality for Democrats is that making the case for the constitutionality of the trial should have been the easy part. They had precedent on their side. Nothing in the language of the Constitution explicitly said a former president can’t stand trial. But only one senator – Bill Cassidy of Louisiana – appeared to shift from a previous position to join the Democrats.
Senate Minority Leader Mitch McConnell, who had reportedly been “pleased” that the House was impeaching Trump, voted no. He, more than anyone in the Senate chamber, knows the mood of his fellow Republicans.
Democrats will now proceed with their case. They may make more heartfelt arguments that could resonate with the majority of Americans who polls indicate favour convicting Trump. Inside the chamber, however, it appears minds are already made up.