The House Democrats prosecuting Trump’s trial for inciting the deadly siege of the Capitol used the video to show how members of the pro-Trump mob searched the building for his vice president, chanting: “Hang Mike Pence!”

Previously unseen security videos showed the view from inside the Capitol as rioters smashed windows and fought with police on January 6, coming within 30 metres of the room where Pence was sheltering with his family. The mob had set up a gallows outside.

The House of Representatives has charged Trump, a Republican, with inciting an insurrection by exhorting thousands of supporters to march on the Capitol on the day Congress was gathered to certify Democrat Joe Biden’s electoral victory.

The rioters stormed the building, sending lawmakers into hiding and leaving five people dead, including a police officer.

The footage highlighted the fact that hundreds of Trump supporters who attacked the building in an attempt to stop the peaceful transfer of power targeted Republicans – whose votes will be needed to convict Trump.

“The mob was looking for Vice-President Pence,” Representative Stacey Plaskett said on Wednesday, narrating footage that showed the crowd chanting “Hang Mike Pence!” and searching for Democratic Speaker Nancy Pelosi.

“President Trump put a target on their backs and then his mob broke into the Capitol to hunt them down,” she said.

Trump had repeatedly said Pence had the power to stop the certification of the election results, even though he did not.

The Democratic House managers prosecuting the case for impeachment, an uphill task in a narrowly divided Senate, said Trump planted the seeds for the riot by encouraging violence and making false claims the election was stolen long before January 6.

“Trump realised last spring that he could lose the November election and began planting seeds of anger among his supporters by saying he could lose only if it was stolen,” Representative Joseph Neguse said.

Conviction, while unlikely, could lead to a vote to bar Trump from running for office again.

Several Republican senators said the security footage was emotional, but many added it did not change their minds.

“He bears some responsibility for what happened that day, but … that doesn’t mean that impeachment is the right way to address it,” said Senator Marco Rubio, who added he thought the best approach was federal prosecution.

Trump’s lawyers, who will have 16 hours to deliver their side of the argument after the House managers are finished, argue his rhetoric was protected by the First Amendment’s guarantee of free speech, and the individuals who breached the Capitol were responsible for their own criminal behaviour.

They also say the trial is politically motivated.

Representative Joaquin Castro cited what he called blatant acts of political intimidation against election workers in states Trump was losing. In Philadelphia, Atlanta and Milwaukee, Castro said, Trump’s supporters tried to use armed force to disrupt the counting of votes.

Trump’s actions threatened the peaceful transfer of power, the Democratic managers said, calling Trump the “inciter in chief”.

“This case is not about blaming an innocent bystander for the horrific violence and harm that took place on January 6,” lead manager Jamie Raskin said as he opened the proceedings. “This is about holding accountable the person singularly responsible for inciting the attack.”

A two-thirds majority in the Senate must vote to convict, which means at least 17 Republicans would have to defy Trump’s popularity among Republican voters. On Tuesday, just six out of 50 Republican senators voted that the trial could move ahead even though Trump’s term ended on January 20.

The Senate trial could conclude as early as Saturday or Sunday.

Trump is the first US president to be impeached twice. His first trial, which stemmed from his efforts to pressure Ukraine to investigate Biden, ended in an acquittal a year ago in what was then a Republican-controlled Senate.