The FBI has warned of possible armed protests being held across the US as Trump supporters and far-right groups call for demonstrations before Joe Biden is sworn in as president.
There are reports of armed groups planning to gather at all 50 state capitols and in Washington DC in the run-up to his 20 January inauguration.
Security will be tight for the event after a pro-Trump mob stormed Congress.
House Democrats say a vote to impeach the president will happen on Wednesday.
They accuse President Trump of “incitement of insurrection” and say the vote will be held unless Vice-President Mike Pence invokes constitutional powers to remove Mr Trump from office. There is no sign Mr Pence is prepared to do so.
Mr Biden and Vice-President-elect Kamala Harris are expected to be sworn in at a ceremony at the Capitol. The Biden team had already urged Americans to avoid travelling to the capital because of the Covid-19 pandemic, a call that is now being repeated by local authorities.
Security officials have said there will be no repeat of the breach seen on 6 January, when thousands of pro-Trump supporters were able to break into the building where members of Congress were voting to certify the election result.
Five people died in the riot, which happened after Mr Trump repeated unsubstantiated claims of fraud in the November vote and encouraged his supporters to march on the Capitol.
Since then, calls for Mr Trump’s resignation, removal from office or impeachment have grown among Democrats and some Republicans. Mr Trump has made no public statements since he was banned from several social media platforms — including Twitter — on Friday.
He became the third US president to be impeached in December 2019 over charges of breaking the law by asking Ukraine to investigate his rival in the presidential election. The Senate cleared him.
Key dates to watch
Tuesday: The House of Representatives will vote on a resolution calling on Vice-President Pence and the cabinet to invoke the 25th Amendment to declare the president unfit for office and remove him immediately. The resolution is likely to pass as Democrats hold a majority, but Mr Pence has shown no sign he is planning to act
Wednesday: Democrats vow to hold a vote on impeachment. As they have a majority, Mr Trump is likely to become the first president to be impeached twice. The single article of impeachment — a formal charge — will then need to be sent to the Senate where a trial will be held but the timeline is not known
20 January: Joe Biden and Kamala Harris are sworn in as president and vice-president
What further protests are planned?
Posts on pro-Trump and far-right online networks have called for protests on a number of dates, including armed demonstrations in cities across the country on 17 January and a march in Washington DC on inauguration day itself.
An internal FBI bulletin, reported by ABC News and other outlets, carries a warning that one group is calling for the “storming” of state, local and federal courthouses around the country if Mr Trump is removed from office early and on inauguration day if he is not.