Up to 15,000 troops authorised for Biden's inauguration

The Pentagon has said it has authorised 15,000 National Guard troops to be deployed for Joe Biden's January 20 inauguration amid fears of more violence by supporters of President Donald Trump.

Already 6,200 are on the ground in Washington, and a total of 10,000 are planned by the coming weekend, said General Daniel Hokanson, chief of the Defense Department's National Guard Bureau on Monday.

Another 5,000 could be deployed by the day of the inauguration, he said.

They will come equipped with riot gear and weapons, but so far they have not been authorised to arm themselves while on the streets of the US capital, he said.

For the moment their mission is to support local police in communications, logistics, and security, he said.

READ MORE: Trump refuses to attend Biden's inauguration, breaking tradition

Criticism after Capitol attack 

Authorising the National Guard to deploy in a law enforcement role, armed and empowered to make arrests, would be a "last resort" if the security situation got out of hand, Hokanson said.

The Pentagon and the Guard have been criticised for a slow response on Wednesday when the US Capitol was besieged by thousands of Trump supporters attacking an undermanned and unprepared Congressional security force.

But Pentagon officials say they were summoned late and did not immediately have with them the required riot gear.

"They did not anticipate that level of violence," said Hokanson.

Earlier Washington Mayor Muriel Bowser, anticipating the possibility of tension around the inauguration, called for people to stay away from the city.

"We are asking Americans not to come to Washington DC for the 59th presidential inauguration on January 20 and to instead participate virtually," she said.

The US National Park Service said it has closed the Washington Monument through January 24 due to continuing threats, from groups involved in last week's pro-Trump riot at the US Capitol, to disrupt Biden's inauguration.

Earlier, the FBI said armed protests are being planned at all 50 state capitals, Washington, DC ahead of Biden's inauguration.

Democrats urge Pence to help oust Trump

Meanwhile, mounting impeachment pressure, the House worked swiftly on Monday to try to oust President Trump from office, pushing the vice president and Cabinet to act first in an extraordinary effort to remove Trump in the final days of his presidency.

Trump faces a single charge – "incitement of insurrection" – in an impeachment resolution that could go to a vote by mid-week. 

First, Democrats called on Vice President Mike Pence to invoke constitutional authority under the 25th Amendment to remove Trump from office before January 20, when Democrat Biden is to be inaugurated.

READ MORE: Democrats seek second Trump impeachment amid Republican doubts

Trump, a 'threat to national security'

In all, these are stunning final moments for Trump's presidency as Democrats and a growing number of Republicans declare that he is unfit for office and could do more damage after inciting a mob that ransacked the US Capitol in a deadly siege on Wednesday.

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

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

READ MORE: More than a dozen people charged over US Capitol violence

Republicans block House resolution

On Monday, a House resolution calling on Vice President Pence to invoke constitutional authority to remove Trump from office was blocked by Republicans.

However, the full House is set to hold a roll call vote on that resolution on Tuesday, and it is expected to pass.

After that, Pelosi said Pence will have 24 hours to respond. Next, the House would proceed to impeachment. A vote could come on Wednesday.

Pence has given no indication he is ready to proceed on such a course, which would involve invoking the 25th Amendment to the Constitution with a vote by a majority of the Cabinet to oust Trump before January 20.

READ MORE: How a security lapse allowed pro-Trump protesters to invade US Capitol