The US Senate has voted 55-45 to block a Republican effort to upend plans for former president Donald Trump's impeachment trial on a charge that he incited the deadly January 6 assault on the US Capitol.
In an early test of the Senate's impeachment drive, five Republicans joined Democrats to reject a motion by Republican Senator Rand Paul that would have required the chamber to vote on whether the trial violates the US Constitution.
Paul and other Republicans contend that the proceedings are unconstitutional because Trump left office last Wednesday and the trial will be overseen by Democratic Senator Patrick Leahy instead of US Chief Justice John Roberts.
"This proceeding, which would try a private citizen and not a president, vice-president or civil officer, violates the Constitution," Paul told his fellow senators after they had been sworn in as jurors for the trial set to begin on February 9.
Democratic Senate Majority Leader Chuck Schumer dismissed Paul's argument as "flat-out wrong" and "a constitutional get-out-of-jail-free card" for presidents guilty of misconduct.
Most of the Senate's 50 Republican lawmakers voted against a motion by Schumer to kill Paul's proposal.
Paul had predicted that support for his move would show the Senate incapable of convicting Trump, which would require 67 votes. But some Republicans described Tuesday's vote and the question of Trump's guilt as separate matters.
There is a debate among scholars over whether the Senate can hold a trial for Trump now he has left office. Many experts have said "late impeachment" is constitutional, arguing presidents who engage in misconduct late in their terms should not be immune from the very process set out for holding them accountable.
Fellow Republican Senator Lisa Murkowski, who has been critical of Trump, rejected Paul's move.
"My review of it has led me to conclude that it is constitutional, in recognising that impeachment is not solely about removing a president, it is also a matter of political consequence," Murkowski told reporters on Tuesday.
Murkowski joined fellow Republican senators Mitt Romney, Susan Collins, Ben Sasse and Patrick Toomey in opposing Paul.
Trump is the only president to have been impeached by the House of Representatives twice and the first to face a trial after leaving power, with the possibility of being disqualified from future public office if convicted by two-thirds of the Senate.
The House approved a single article of impeachment on January 13, accusing him of inciting an insurrection with an incendiary speech to supporters before they stormed the Capitol on January 6. A police officer and four others died in the melee.
At least 17 Republicans would need to join all 50 Democrats for Trump to be convicted, which appears unlikely to be reached. Trump remains a powerful force among Republicans and his supporters have vowed to mount election challenges to lawmakers in the party who support conviction.
Australian Associated Press