WASHINGTON, United States (AFP) — US President Donald Trump was told 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.

As his presidency imploded, Trump signalled a final, unrepentant display of division by announcing on Twitter that he will skip the inauguration of Joe Biden on January 20.

“To all of those who have asked, I will not be going,” he tweeted.

Biden responded this was “a good thing,” branding Trump an “embarrassment”.

However, Biden showed how wary he is of the growing rush to impeach Trump — and deepen the national political war — over his incitement of crowds who stormed Congress on Wednesday.

“That is a judgment for the Congress to make,” Biden said, adding that the “quickest” way to get Trump out was for him and Vice President-elect Kamala Harris to take over in 12 days.

“I am focused now on us taking control as president and vice president on the 20th and to get our agenda moving as quickly as we can.”

Two days after Trump sent a mob of followers to march on Congress, his presidency is in freefall, with allies walking away and opponents sharpening their teeth.

House Speaker Nancy Pelosi warned that Democrats will launch impeachment proceedings unless Trump resigns 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 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 a president could be ready next week.

“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 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”.