US President Donald Trump came under pressure Friday to step down or face impeachment, as the top Democrat in Congress announced she had discussed with the military how to block the "unhinged" leader from the nation's nuclear arsenal.
Two days after Trump incited followers to storm Congress, his presidency is in freefall, with allies walking away and calls for his removal accelerating.
House Speaker Nancy Pelosi warned that Democrats will launch impeachment proceedings unless Trump leaves willingly, or Vice-President Mike Pence invokes the 25th Amendment, where the Cabinet removes the president.
"If the President does not leave office imminently and willingly, the Congress will proceed with our action," Pelosi wrote.
In a jaw-dropping moment, Pelosi also revealed she had spoken Friday with the Chairman of the Joint Chiefs of Staff Mark Milley about "preventing an unstable president from initiating military hostilities or accessing the launch codes and ordering a nuclear strike."
"The situation of this unhinged president could not be more dangerous, and we must do everything that we can to protect the American people," Pelosi wrote.
Democrats in the House of Representatives, who already impeached Trump in a traumatic, partisan vote in 2019, said the unprecedented second impeachment of the president could be ready next week. Articles of impeachment have been drafted but they have yet to be introduced.
"We can act very quickly when we want to," Representative Katherine Clark told CNN.
Whether Republican leaders of the Senate would then agree to hold a lightning fast impeachment trial before the January 20 transition is another matter.
In the House, the senior Republican representative Kevin McCarthy said "impeaching the president with just 12 days left in his term will only divide our country more."
Trump, whose incitement of crowds assaulting Congress capped relentless efforts to overturn Biden's November 3 election win, finally conceded defeat on Thursday and appealed for calm.
However, the evidently reluctant concession, in which Trump failed to congratulate Biden or directly admit defeat, was too little, too late to calm outrage over his role in the Capitol invasion.
Senator Ben Sasse, one Republican who says he will "definitely consider" impeachment, recommended that Trump at minimum step back and let his vice-president run the show in the dying days.
"I think the less the president does over the next 12 days the better," he told NPR radio.