Ten House Republicans voted to impeach Donald Trump, turning against the president and their party to join with Democrats in its charge of "incitement to insurrection".
Among the highest-ranking was Wyoming's Liz Cheney, chair of the House Republican Conference, who faced calls to step down from GOP leadership over her support of impeaching the president.
She was joined by John Katko, of New York, Adam Kinzinger, of Illinois, Anthony Gonzalez, of Ohio, Tom Rice, of South Carolina, David Valadao, of California, Fred Upton and Peter Meijer of Michigan, and Jamie Herrera Beutler and Dan Newhouse, both from Washington.
Read more: Trump impeachment timeline
As the process now moves toward to the upper chamber of Congress, at least four Republican senators have indicated they were either undecided or considering supporting impeachment, including majority leader Mitch McConnell.
He is joined by Senators Lisa Murkowski, of Alaska, Ben Sasse, of Nebraska, and Pat Toomey, of Pennsylvania.
Here are the House Republicans who voted to impeach the 45th president of the United States, and the Senate colleagues who may join them.
Liz Cheney, Wyoming's at-large district
Ms Cheney, the third-highest ranking Republican in the House and Wyoming's only member in Congress, indicated her support for the impeachment of Trump for stoking the mob into rioting at the Capitol.
“The President of the United States summoned this mob, assembled the mob, and lit the flame of this attack,” Ms Cheney said in a statement before the vote. “Everything that followed was his doing. None of this would have happened without the President.”
John Katko, New York's 24th district
The former federal prosecutor was the first Republican to indicate he would vote for impeachment, opening the gates for the handful that turned on the outgoing president. He voted against the first impeachment of the president.
“To allow the president of the United States to incite this attack without consequence is a direct threat to the future of our democracy,” he said in a statement. “For that reason, I cannot sit by without taking action."
Adam Kinzinger, Illinois’s 16th district
Mr Kinzinger is a frequent critic of Mr Trump and has called on Mike Pence to invoke the 25th Amendment following the Capitol riot.
"There is no doubt in my mind that the President of the United States broke his oath of office and incited this insurrection," Mr Kinzinger said before the vote. "If these actions--the Article II branch inciting a deadly insurrection against the Article I branch--are not worthy of impeachment, then what is an impeachable offence?"
Fred Upton, Michigan's 6th district
The former chair of the House Energy and Commerce Committee voted against the first impeachment but said Congress must hold the president to account and send a clear message.
"I would have preferred a bipartisan, formal censure rather than a drawn-out impeachment process," he said before the vote. "I fear this will now interfere with important legislative business and a new Biden Administration. But it is time to say: Enough is enough."
Peter Meijer, Michigan’s 3rd district
The newly sworn-in Republican released a statement saying he wrestled with the division the vote will cause and the precedent it would establish to due process, but that the impeachment was a call to action to reflect on the Capitol riots and ways to correct them.
“My job is to apply my best judgement of the article of impeachment that is on the floor of the US Congress. With the facts at hand, I believe the article of impeachment to be accurate,” he said.
“The president betrayed his oath of office by seeking to undermine our constitutional process, and he bears responsibility for inciting the violent acts of insurrection last week.”
Jaime Herrera Beutler, Washington's 3rd district
Ms Beutler made her intentions to impeach the president known on Twitter, saying he acted against his oath of office and "incited a riot to halt the peaceful transfer of power".
"Hours went by before the president did anything meaningful to stop the attack. Instead, he and his lawyer were busy making calls to senators who were still in lockdown, seeking support to further delay the Electoral College certification," she said in a tweet.
Dan Newhouse, Washington's 4th district
Another Republican who did not support the 2019 impeachment, Mr Newhouse said voiting against the latest attempt would be a vote to validate violence at the Capitol.
"It is also a vote to condone President Trump’s inaction," he said before the vote. "He did not strongly condemn the attack nor did he call in reinforcements when our officers were overwhelmed. Our country needed and leader, and President Trump failed to fulfil his oath of office.”
Anthony Gonzalez, Ohio's 16th district
Mr Gonzalez said in a statement the president helped organize and incite a mob in an attempt to prevent Congress certifying the election results.
“During the attack itself, the president abandoned his post while many members asked for help, thus further endangering all present,” he said. “These are fundamental threats not just to people’s lives but to the very foundation of our republic.”
Tom Rice, South Carolina’s 7th district
Mr Rice was one of the few Republicans who did not indicate their vote before voicing it in the House. Making the vote even more unexpected were his comments to local news broadcaster News13 on Monday that he didn’t support impeaching the president.
“Trump acted recklessly last Wednesday, but he only has nine days left in his term,” his statement said. “Let’s not stoke further division.”
David Valadao, California’s 21st district
The other surprise Republican to throw their hat in with the Democrats was Mr Valadao of California, who said in a tweet following the vote that Mr Trump was the driving force of the Capitol riot.
“Speaker Pelosi has thrown precedent and process out the window by turning what should be a thorough investigation into a rushed political stunt. I wish, more than anything, that we had more time to hold hearings to ensure due process,” he said.
“Unfortunately, speaker Pelosi did not afford us that option. Based on the facts before me, I have to go with my gut and vote my conscience. I voted to impeach president Trump. His inciting rhetoric was un-American, abhorrent, and absolutely an impeachable offence. It’s time to put country over politics.”
At least 17 Republicans in the Senate need to support impeachment to forcefully remove Mr Trump from the White House before his term ends on 20 January.
Here are four that have so far indicated they could swing either way on the unprecedented vote.
Mitch McConnell, Senate majority leader from Kentucky
Quoting sources “familiar with his thinking”, The New York Times reported that Mr McConnell was happy with the push to impeach the president and that it would help purge the GOP of Mr Trump’s legacy.
Publicly, however, he says he hasn’t made a decision one way or the other.
"While the press has been full of speculation, I have not made a final decision on how I will vote, and I intend to listen to the legal arguments when they are presented to the Senate," Mr McConnell told Senate Republicans.
Lisa Murkowski, Alaska
Like Alaska, Ms Murkowski often stands apart from the rest of the contiguous US Republicans, most notably in her break from the party in her objections to replacing Ruth Bader Ginsburg in the Supreme Court before the presidential election. She did, however, tow the party line in appointing Amy Coney Barrett when the vote went ahead.
“I want him to resign. I want him out. He has caused enough damage,” she told the Anchorage Daily News.
Ben Sasse, Nebraska
A frequent critic of Mr Trump, Mr Sasse said he would “definitely consider” articles of impeachment brought by the House, but that it would be weighed against what is best for uniting the country.
"I believe the president has disregarded his oath of office. He swore an oath to the American people to preserve, protect and defend the Constitution. He acted against that," Mr Sasse said in an interview with CBS This Morning.
"What he did was wicked. That said, the question of what the House does now and how the Senate responds to it over the next 12 days is a critically important question, but the most important question is the prudential one is how we bring the country back together."
Pat Toomey, Pennsylvania
Mr Toomey has already said he believes the president committed impeachable offences, and has previously condemned his efforts to undermine the results of the election, saying he had “descended into a level of madness” since his loss.
But that might not be enough to vote for impeachment. Speaking to Fox News, he said: “I'm not sure it's desirable to attempt to force him out, what, a day or two or three prior to the day on which he’s going to be finished anyway … so I'm not clear that's the best path forward.”