Donald Trump’s impeachment trial is getting under way in the Senate today, but Democrats have already claimed the process for the hearing is unfair.
The Republican president, who is 4,000 miles away from Washington in Davos, Switzerland, is charged with abuse of power and obstruction of Congress after investigations by the lower House of Representatives, which the Democrats control.
The case has now moved to the upper house, the Republican-dominated Senate, which will have the final say and decide whether he is guilty.
But the vote is expected to be mostly along party lines and it is therefore unlikely he will be removed from office.
Mr Trump is accused of trying to pressure Ukraine into investigating his political rival, Democrat Joe Biden, by threatening to withhold military aid.
The US president has dismissed the charges as a “hoax” and a “witch-hunt”.
Democrats have criticised the proposals for how the trial will be run.
Leading congressman Adam Schiff said: “It does not prescribe a process for a fair trial, and the American people desperately want to believe that the Senate will give both the president and the House of Representatives a fair trial.
“We will be appealing as managers to the senators today to live up to the oath they have just taken, to do impartial justice and to hold a fair trial.”
He also told reporters outside: “This is not a process for a fair trial, this is the process for a rigged trial” and called it a “cover-up.”
Senate majority leader Mitch McConnell, a Republican, is proposing the two sides will each have 24 hours to present their arguments, spread over four 12-hour days.
But Democrats have protested that the rules would mean some arguments would be pushed into the early hours and make it harder to introduce evidence.
The proposals also put off any votes on witnesses until later in the process, rather than at the start, as Democrats had demanded.
Democrats claim Mr Trump abused his power by pressuring Ukraine to help him politically, and obstructed Congress when it tried to find out what happened.
After the four days of opening arguments, senators will be allowed up to 16 hours for questions to the prosecution and defence, followed by four hours of debate.
Only then will there be votes on calling other witnesses.
Senate rules say the trial must proceed six days a week – excluding Sundays – until it is resolved.
There’s some question about whether it will be finished by 4 February, the day of Mr Trump’s State of the Union speech.
White House officials say that appointment remains for now but Mr Trump can ask the House to postpone it.
Only two other US presidents in history have been impeached – Andrew Johnson in 1868 and Bill Clinton in 1998.
Both Mr Johnson and Mr Clinton were acquitted in the Senate, while in 1974 Richard Nixon faced impeachment but resigned before a full vote in the House of Representatives.