With eight days remaining in Trump's term in office, the House of Representatives was poised on Wednesday to pass an article of impeachment accusing the Republican of inciting insurrection in a speech to his followers on January 6 before a mob of them stormed the Capitol, leaving five dead.
That would trigger a trial in the still Republican-controlled Senate, although it was unclear if enough time or political appetite remained to push Trump from office.
Even as the Democratic-led House debated a resolution that urged Pence to invoke the 25th Amendment of the US Constitution to expel Trump from office, Pence sent a letter to House Speaker Nancy Pelosi that said he would not comply.
"I do not believe that such a course of action is in the best interest of our Nation or consistent with our Constitution," he said.
Trump's iron grip on his party showed further signs of weakening as at least three Republicans, including a member of the House leadership, said they would vote for his historic second impeachment.
Liz Cheney, the No 3 House Republican, said: "There has never been a greater betrayal by a President of the United States of his office and his oath to the Constitution."
Trump "summoned this mob, assembled the mob, and lit the flame of this attack" on the Capitol last Wednesday, Cheney, the daughter of former Republican Vice President Dick Cheney, said in a statement, adding: "I will vote to impeach the president."
Two other Republican House members, John Katko and Adam Kinzinger, said they would also vote for impeachment.
Their announcements came as Republican leaders in the House refrained from urging their members to vote against impeaching Trump, saying it was a matter of individual conscience.
At a meeting to set the rules for Wednesday's impeachment vote, Democratic Representative David Cicilline told the House Rules Committee that the impeachment drive had the support of 217 lawmakers - enough to impeach Trump.
Cicilline, who helped craft the impeachment measure, said Trump "has had almost a week to do the right thing. He has refused to resign, he has failed to take responsibility, he has demonstrated no remorse.”
The New York Times reported that the Republican majority leader of the US Senate, Mitch McConnell, was said to be pleased about the Democratic impeachment push, suggesting Trump's party was looking to move on from him after last week's stunning attack on Congress.
McConnell believes the impeachment effort will make it easier to purge Trump from the party, the Times said.
If Trump is impeached by the House, he would have a trial in the Senate to determine his guilt. A two-thirds majority of the Senate is needed to convict him, meaning at least 17 Republicans in the 100-member chamber would have to vote for conviction.
"I don't think you would have a hard time finding 17 Republicans to convict" with a tightly drawn article of impeachment, a former Senate Republican leadership aide told Reuters. "I think for McConnell, there's a very strong impulse for this (the Capitol assault) not to define the party."
In his first public appearance since last Wednesday's riot, Trump showed no contrition for his speech, in which he repeated his false claim that President-elect Joe Biden's victory was illegitimate. Biden will be sworn in as president on January 20.
"What I said was totally appropriate," Trump told reporters as he left for a trip to the US-Mexico border wall near Alamo, Texas, his first public foray since the assault on the Capitol.
McConnell has said no trial could begin until the chamber returns from its recess on January 19.
But Democratic Minority Leader Chuck Schumer, who is set to become the majority leader after two Democrats from Georgia are seated and Vice President-elect Kamala Harris is sworn in, told reporters the Senate could be recalled to handle the matter.
PARTISAN FIGHT
In a debate ahead of the House vote on the 25th Amendment resolution, Democrats pushed Republican lawmakers to disavow Trump's false allegation that Biden's victory was illegitimate. That claim enraged Trump's supporters and prompted the violence in Washington that killed five including a police officer.
Republicans refused to concede the point and said their unsuccessful effort last week to challenge the results of the election was justified.
The resolution calls on Pence to invoke Section 4 of the 25th Amendment, a never-before used power that allows a majority of the Cabinet to strip the president of power if he or she is deemed unable to discharge the office's duties.
But Democrats say Trump's actions demand a response.
Democrats could also use an impeachment trial to push through a vote blocking Trump from running for office again.
Rather than a two-thirds vote, only a simple Senate majority is needed to disqualify Trump from future office. There is disagreement among legal experts as to whether a conviction on an impeachment charge would be needed before a disqualification vote.
A different part of the Constitution, the 14th Amendment, also provides a procedure for disqualifying Trump from future office with a simple majority of both chambers.
Trump has said he plans to run again in 2024.
