Donald Trump’s grip on the US presidency appeared increasingly tenuous on Saturday as Democrats advanced plans to impeach him for a second time, political allies continued to abandon him and Twitter banned his account, removing his most powerful way to spread lies and incite violence.

Adding to the pressure in the aftermath of Wednesday’s deadly riot in the US Capitol building by Trump supporters, one Republican senator, Lisa Murkowski of Alaska, openly called for the president’s removal.

“I want him to resign. I want him out. He has caused enough damage,” she said, punctuating the wave of disgust that followed Trump’s goading of a mob seeking to overturn his election defeat by Joe Biden.

Five people died, including a police officer who confronted rioters and a rioter shot by law enforcement. Multiple arrests have been made, among them a Florida resident photographed walking off with the lectern of the House speaker, Nancy Pelosi.

The US attorney’s office said a 70-year-old Alabama man was charged with possession of molotov cocktails and assault weapons after his pickup truck was discovered packed with homemade bombs and guns.

Articles of impeachment charging Trump with inciting an insurrection and having “gravely endangered the security of the United States” and its institutions, were set to be introduced in the US House of Representatives as early as Monday, Pelosi said.

The move is part of a multi-pronged approach by Democrats pressing for Trump’s removal ahead of Biden’s inauguration on 20 January.

Pelosi, who spoke to the leader of the US military seeking to ensure Trump cannot launch a nuclear attack in his remaining days in office, has also called for his removal via the 25th amendment, which provides for the ejection of a president deemed unable to fulfil his duties.

The treasury secretary, Steven Mnuchin, was reportedly among officials to discuss such a course. But it seems unlikely, particularly as cabinet members who would participate in the process have resigned.

White House sources have asserted Trump will not resign or turn over power to Vice-President Mike Pence to seek a pardon, so a second and high-speed impeachment looms. In his first impeachment, over approaches to Ukraine for dirt on political rivals, Trump was acquitted by a Republican-held Senate.

This time, more Republican senators are indicating support. Murkowski became the first, telling the Anchorage Daily News: “I think he should leave.

“He’s not going to appear at the inauguration. He hasn’t been focused on what is going on with Covid. He’s either been golfing or he’s been inside the Oval Office fuming and throwing every single person who has been loyal and faithful to him under the bus, starting with the vice-president.

“He only wants to stay there for the title. He only wants to stay there for his ego. He needs to get out. He needs to do the good thing, but I don’t think he’s capable of doing a good thing.”

Murkowski’s intervention was dramatic, echoing the delegation of Republicans who went to Richard Nixon and told him to resign before he was impeached over Watergate in 1974.

Ben Sasse, Republican senator for Nebraska, was also critical, accusing Trump of a “dereliction of duty” and indicating he was open to impeachment.

Many more Republicans would have to turn for the president to be convicted and removed, however, even if a trial could be held before inauguration day. A House impeachment vote later this week would send the case for trial, but Mitch McConnell, the Republican Senate leader, has indicated the chamber would not consider proceedings until after the inauguration.

Several Republicans have said they would not support impeachment. Jeff Flake, a Trump critic and former senator for Arizona, told CNN on Saturday it would be better if Trump “just went away”.