House Speaker Nancy Pelosi said Sunday the House will proceed with legislation to impeach President Donald Trump as she pushes the vice president and the Cabinet to invoke constitutional authority force him out, warning that Trump is a threat to democracy after the deadly assault on the Capitol.

The House action could start as soon as Monday as pressure increases on Trump to step aside. A Republican senator, Pat Toomey of Pennsylvania, joined Republican Sen. Lisa Murkowski of Alaska in calling for Trump to “resign and go away as soon as possible.”

A stunning end to Trump’s final 10 days in office was underway as lawmakers warned of the damage the president could still do before Joe Biden was inaugurated Jan. 20. Trump, holed up at the White House, was increasingly isolated after a mob rioted in the Capitol in support of his false claims of election fraud.