The Democratic-controlled House of Representatives is expected to hold a vote on the matter as early as Wednesday.

Passage would make Mr Trump the only president in US history to be impeached twice.

House Democrats impeached Mr Trump in December 2019 for pressuring Ukraine to investigate Joe Biden, now the Democratic President-elect, but the Republican-controlled Senate voted not to convict him.

If Mr Trump is convicted, he might be prevented from running again for the presidency or ever holding public office.

"I can report that we now have the votes to impeach," tweeted David Cicilline, a Democratic Congressman from Rhode Island said.

The article of impeachment states that Mr Trump thus far faces a solitary charge — "incitement of insurrection".

"President Trump gravely endangered the security of the United States and its institutions of Government," reads the four-page impeachment bill.

"He threatened the integrity of the democratic system, interfered with the peaceful transition of power, and imperilled a coordinate branch of Government.

"He thereby betrayed his trust as President, to the manifest injury of the people of the United States.

"He will remain a threat to national security, democracy, and the Constitution if allowed to remain in office."

Democrat representative Jim McGovern, the chairman of the House Rules Committee, said he expected the impeachment article to pass the House.

"What this president did is unconscionable, and he needs to be held to account," Mr McGovern told CNN.

Scott Dworkin, founder of the Democratic Coalition Against Trump, said that 215 members of the House had agreed to vote to impeach.

Politico cited a congressional aide as saying the article of impeachment had at least 218 co-sponsors.

Republican Senator Pat Toomey said he doubted Mr Trump could be impeached before Mr Biden was inaugurated, even though a growing number of lawmakers said the step was necessary to ensure Mr Trump never held elected office again.

"I think the President has disqualified himself from ever, certainly, serving in office again," Mr Toomey said.

"I don't think he is electable in any way."

Riots lead to calls for impeachment

The impeachment move came after thousands of Mr Trump's supporters stormed the Capitol last week.

It forced politicians who were certifying Mr Biden's election victory into hiding, in a harrowing assault on the heart of American democracy that left five dead.

It came shortly after Mr Trump addressed thousands of his supporters, who had rallied near the White House.

"We will not let them silence your voices," Mr Trump told the protesters as he repeated unfounded claims of election fraud.

"We will never concede. It doesn't happen. You don't concede when there's theft involved."

Dozens of people who attacked police officers, stole computers and smashed windows at the Capitol have been arrested for their role in the violence, and officials have opened 25 domestic terrorism investigations.

House Speaker Nancy Pelosi, many of her fellow Democrats and a handful of Republicans say Mr Trump should not be trusted to serve out his term, which ends on January 20.

"In protecting our constitution and our Democracy, we will act with urgency, because this President represents an imminent threat to both," Ms Pelosi wrote to her fellow House Democrats on Sunday.

Before the impeachment article was introduced, Republicans blocked an effort to immediately consider a resolution asking Vice-President Mike Pence to invoke the US constitution's never-used 25th Amendment to remove an unfit president.

The House is expected to vote on Tuesday (local time) on the resolution calling for use of the 25th Amendment, which allows the vice-president and the Cabinet to remove a president who is incapable of fulfilling his duties.

Mr Pence and his fellow Republicans have shown little interest in invoking the amendment.

Some Republicans warn against impeachment.

"They're not only going to create bad feelings in Congress, they're really going to create tremendously bad feelings in America," said Congressman Jeff Van Drew of New Jersey.

Nevertheless, Republican Senator Ben Sasse said he would take a look at any articles the House sent over.

Adam Kinzinger, a frequent Republican critic of Mr Trump, said he would "vote the right way" if the matter were put in front of him.

Mr Trump acknowledged in a video statement after the attack that a new administration would take office on January 20, but he has not appeared in public.

Twitter and Facebook have suspended his accounts, citing the risk of him inciting violence.