House Speaker Nancy Pelosi said the U.S. House of Representatives will proceed with legislation to impeach President Trump as she pushes Vice President Pence and the Cabinet to use constitutional authority to force him out. She warned that Trump is a threat to democracy after Wednesday’s deadly assault on the Capitol.

Pressure for Trump to step aside increased over the weekend. A Republican senator, Patrick Toomey of Pennsylvania, joined Senator Lisa Murkowski, a Republican from Alaska, in calling for Trump to “resign and go away as soon as possible.”

Lawmakers warned of the damage the president could do before President-elect Joe Biden’s inauguration on January 20. Trump has become increasingly isolated after a mob rioted in the Capitol in support of his false claims of election fraud.

Judges across the country, including some nominated by Trump, repeatedly dismissed cases, and Attorney General William Barr, a Trump ally, said there was no sign of widespread fraud. Pelosi emphasized the need for quick action.

“We will act with urgency, because this President represents an imminent threat,” Pelosi said in a letter late Sunday to colleagues. “The horror of the ongoing assault on our democracy perpetrated by this President is intensified and so is the immediate need for action.”

On Monday, Pelosi’s leadership team will seek a vote on a resolution calling on Vice President Mike Pence and Cabinet officials to invoke the 25th Amendment — a process in which the vice president would become president if Pence and those officials determine Trump is “unable to discharge the powers and duties of his office.” A full House vote is expected Tuesday.

After that, Pence and the Cabinet would have 24 hours to act before the House would move toward impeachment.

During an interview on “60 Minutes” aired Sunday, Pelosi invoked the Watergate era when Republicans in the Senate told President Richard Nixon, “It’s over.”

“That’s what has to happen now,” she said.

With impeachment planning intensifying, Toomey said he doubted impeachment could be done before Biden is inaugurated, even though a growing number of lawmakers say that step is necessary to ensure Trump can never hold elected office again.

“I think the president has disqualified himself from ever, certainly, serving in office again,” Toomey said. “I don’t think he is electable in any way.”

Murkowski, long exasperated with the president, told the Anchorage Daily News on Friday that Trump simply “needs to get out.” A third, Senator Roy Blunt, a Republican from Missouri, did not go that far, but on Sunday he warned Trump to be “very careful” in his final days in office.

Democrats’ strategy would be to condemn the president’s actions swiftly but delay an impeachment trial in the Senate for 100 days. That would allow President-elect Joe Biden to focus on other priorities as soon as he is inaugurated.

— Associated Press