Democrats prosecuting Donald Trump’s impeachment said the Capitol invaders believed they were are acting on “the president’s orders” to storm the building and stop the joint session of Congress that was certifying Joe Biden’s election.

The prosecutors are wrapping up their opening presentation, describing in stark, personal terms the horror they faced that day and drilling down on the public and explicit instructions Mr Trump gave his supporters — both in the weeks before the January 6 attack and at his midday rally that unleashed the mob on the Capitol.

They presented videos of rioters, some posted to social medial by the rioters themselves, talking about how they were doing it all for Mr Trump.

“They truly believed that the whole intrusion was at the president’s orders,” said Diana DeGette, of Colorado. “The president told them to be there.”

Mr Trump’s lawyers will launch their defence on Friday.

At the White House, President Biden said he believed “some minds may be changed” after senators saw chilling security video on Wednesday of the deadly insurrection at the Capitol, including of rioters searching menacingly for House Speaker Nancy Pelosi and Vice President Mike Pence.

President Biden said he did not watch any of the previous day’s proceedings live but later saw news coverage.

The never-before-seen audio and video released Wednesday is now a key exhibit in Mr Trump’s impeachment trial as lawmakers prosecuting the case argue he should be convicted of inciting the siege.

Democrats are using their remaining hours of arguments to lay out the physical and mental harm caused by the attack, discuss Mr Trump’s lack of action as it unfolded and do a final presentation on the legal issues involved.

Videos of the siege have been circulating since the day of the riot, but the graphic compilation shown to senators on Wednesday amounted to a more complete narrative, a moment-by-moment retelling of one of the nation’s most alarming days.

It offered fresh details into the attackers, scenes of police heroism and staff whispers of despair. And it showed how close the country came to chaos over the certification of Mr Trump’s defeat to President Biden.

The footage showed the mob smashing into the building, rioters engaging in hand-to-hand combat with police and audio of Capitol police officers pleading for back-up.

It underscored how dangerously close the rioters came to the nation’s leaders, shifting the focus of the trial from an academic debate about the Constitution to a raw retelling of the assault.

Rioters were seen roaming the halls chanting “Hang Mike Pence”, some equipped with combat gear. Outside, the mob had set up a makeshift gallows. And in one wrenching moment, police were shown shooting and killing a San Diego woman, Ashli Babbitt, as the mob tried to break through doors near the House Chamber.

Mr Pence, who had been presiding over a session to certify President Biden’s election victory over Mr Trump — thus earning Mr Trump’s censure — was shown being rushed to safety, where he sheltered in an office with his family just 100 feet from the rioters.

Ms Pelosi was seen being evacuated from the complex as her staff hid behind doors in her suite of offices.

Though most of the Senate jurors seem to have made up their minds, making Mr Trump’s acquittal likely, they sat riveted as the jarring video played in the chamber.

Earlier in the day, prosecutors laid out their case by methodically linking Mr Trump’s verbal attacks on the election to the violence that resulted.

Mr Trump did nothing to stem the violence and watched with “glee”, the Democrats said, as the mob ransacked the building. Five people died.

The goal of the presentation was to cast Mr Trump not as an innocent bystander but rather as the “inciter in chief” who spent months spreading falsehoods about the election.

Using evocative language meant to match the horror of the day, prosecutors compared Mr Trump to a fire chief who delights in seeing fires spread, not extinguished, and they compared his supporters to a cavalry in war.

The Trump legal team takes the floor on Friday and Saturday for up to 16 hours to lay out its defence.