Democrats plunged forward on Friday with plans to impeach Donald Trump over his role in inciting a violent mob attack on the Capitol, picking up some potential Republican support to move as early as next week to try to force the President from office just as his term is drawing to a close.

Speaker Nancy Pelosi said the US House of Representatives would move to impeach Trump if he did not resign “immediately”, appealing to Republicans to join the push to force him from office.

The prospect of forcing Trump from office in less than two weeks appeared remote given the logistical and political challenges involved and the requirement of a two-thirds majority in the Senate.

But the push unfolded amid a sense of national crisis following the Capitol siege as White House resignations piled up and some Republicans appeared newly open to the possibility, which could also disqualify Trump from holding political office in the future.

In a letter to members of the House, the Speaker invoked the resignation of Richard M. Nixon amid the Watergate scandal, when Republicans had prevailed upon the then President to resign and avoid the ignominy of an impeachment.

“Today, following the President’s dangerous and seditious acts, Republicans in Congress need to follow that example and call on Trump to depart his office — immediately,” she wrote. “If the president does not leave office imminently and willingly, the Congress will proceed with our action.”

Pelosi said she had spoken with Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, about “preventing an unstable President from initiating military hostilities or accessing the launch codes”.

The letter came as the momentum for impeachment was rapidly growing on Friday among rank-and-file Democrats across the party’s ideological spectrum.

Representative Katherine Clark of Massachusetts, the No. 4 Democrat, said that if Vice-President Mike Pence would not invoke the 25th Amendment to forcibly relieve Trump of his duties, Democrats were prepared to act on impeachment by the middle of next week.

An aide to Pelosi said on Friday that she still had not heard from Pence, despite putting intense public pressure on him to act. But Pence was said to be opposed to doing so, and she was making plans to move ahead, convening a call with Democrats at noon.

Senator Ben Sasse, Republican of Nebraska, a frequent critic of Trump, said he would “definitely consider whatever articles they might move, because 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,” Sasse said on CBS. “What he did was wicked.”

The House is next scheduled to be in session on Monday, meaning that articles of impeachment could not be introduced until then. On Friday, Clark said on Twitter that Democrats were working to find “the quickest path to hold Trump accountable”, but added that they faced “obstruction and attempts to delay us by the GOP (Republican) defenders”.

New York Times News Service