The House select committee investigating the January 6 attack on the Capitol presented evidence on Thursday that Donald Trump was told his last-gasp attempt to overturn the results of the 2020 election was unlawful but forged ahead anyway.

Trump then pressured his vice-president, Mike Pence, to reject a tally of state electors as part of a plot that brought the country “dangerously close to catastrophe”, the panel heard.

With live witnesses and recorded depositions from its yearlong investigation, the panel offered a dramatic accounting of the days and hours that preceded the assault. Chilling new evidence also detailed the frantic moments after rioters stormed the Capitol, as Pence was rushed from the Senate chamber to a secure underground location.

“Approximately 40 feet – that’s all there was – 40 feet between the vice-president and the mob,” said the California congressman Pete Aguilar, a Democrat who led the panel’s third hearing. “Make no mistake about the fact that the vice-president’s life was in danger.”

The committee spent the majority of the hearing dissecting the “completely nonsensical and antidemocratic” theory, devised by the conservative law professor John Eastman and embraced by Trump, that suggested Pence had the authority to reverse the results of the 2020 election. The vice-president has no such power.

“Trump wanted Mike Pence to do something no other vice-president has ever done,” Congressman Bennie Thompson, chairman of the committee and a Democrat of Mississippi, said opening the hearing. “We were fortunate for Mr Pence’s courage.”

Trump was told repeatedly that the plan was unlawful, according to witnesses and testimony from his closest advisers. Yet in the final days before Congress was due to certify the election results Trump increased his public and private pressure campaign on his loyal lieutenant to do his bidding.

“What the president wanted the vice-president to do was not just wrong, it was illegal and unconstitutional,” Congresswoman Liz Cheney, a Republican of Wyoming and the committee’s vice-chair, said on Thursday.

Squeezed between a president who refused to accept defeat and a constitution that provided him no such power to change the course of the election, the vice-president chose the constitution, those who advised him testified on Thursday.

Greg Jacob, who served as counsel to Pence when he was vice-president, told the panel that Eastman’s plot to nullify the results of the 2020 election was unlawful from its conception – and Eastman knew it.

During a meeting with Eastman on 4 January, Jacob testified that Eastman “acknowledged” that the strategy would violate the Electoral Count Act, the 19th-century law that Trump pressured Pence to exploit. In an exchange the next day, Eastman conceded that if the supreme court heard a challenge to his interpretation of the act, it would have been rejected, 9-0.

The second witness, retired judge and informal Pence adviser J Michael Luttig, said that if Trump had succeeded, it would have “plunged America into what I believed would have been tantamount to a revolution” and “the first constitutional crisis since the founding of the Republic”.

“I would have laid my body across the road before I would have let the vice-president overturn the 2020 presidential election on the basis of that historical precedent,” the staid former judge said.

A federal judge ruled in March that Trump and Eastman “more likely than not” had committed felonies in their efforts to overturn the 2020 election, including obstructing the work of Congress and conspiring to defraud the American people. The committee showed a clip of Trump White House attorney Eric Herschmann testifying that he told Eastman, “get a great effing criminal defense lawyer – you’re gonna need it.”

The committee provided a cinematic accounting of a call between Trump and Pence on the morning of 6 January that turned “pretty heated”, according to Ivanka Trump who was in the Oval Office with her siblings during the exchange. “It was a different tone than I heard him take with the vice-president before.”

A top aide to Ivanka testified that Trump called Pence “the p-word” during the call.

Early drafts of the speech Trump delivered at a rally on the Ellipse before the riot, when he encouraged his supporters to “fight like hell” for his presidency, included no reference to the vice-president, Aguilar said. But Trump changed the remarks to sharply criticize Pence, imploring him to find the “courage” to overturn the election.

The committee also played testimony showing that Trump was told of the violence breaking out in his name at the Capitol before he tweeted at 2.24pm that Pence did not have the “courage to do what should have been done”. In the moments after Trump sent the tweet, the crowds both inside and outside “surged” and overwhelmed law enforcement officers.

A montage played during the hearing showed rioters threatening to drag Pence through the streets and chanting “bring out Pence” and “hang Mike Pence” near where a gallows had been erected outside the Capitol.

The committee displayed an email from Eastman to Trump’s personal lawyer, Rudy Giuliani, sent days after the Capitol riot asking to be put on a potential list to receive a presidential pardon. A pardon was never granted.

Relying on emails written by Eastman, the committee argued that the law professor knew the scheme involving an alternative slate of electors from a handful of states Trump was disputing was unlawful. But he nevertheless presented it to the White House as a viable course of action as early as 13 December 20202, according to emails released in court filings.

Crucially, however, the state legislatures had still not met by that date to certify an alternate Trump slate of electors, which Eastman showed in emails that he knew needed to happen in order for his delicate scheme to have any chance of success.

Eastman also undermined the scheme when he admitted in emails on 19 December 2020, released in court filings, that “unless those electors get a certification from their State Legislators”, the Trump slates would be “dead on arrival in Congress”.

The emails showed Eastman knew the plan rested on states certifying Trump slates. But when he presented a memo to Pence in January 2021 attesting to the existence of Trump slates – that did not actually exist – he revealed corrupt intent to obstruct proceedings on 6 January, the panel believes.

No state legislatures ultimately certified an alternate slate of electors for Trump. The Trump White House appears to have participated in a related scheme to send fake Trump slates to Congress, though those were not introduced at the certification on the day of the attack.

The opening primetime hearing last week, which drew more than 20 million viewers, focused on placing Trump at the heart of a sprawling “seven-part” plot to overturn an election the committee says he knew he lost. The second hearing traced the origins and spread of Trump’s stolen-election myth.

Recorded testimony from Pence’s former chief of staff, Marc Short, also played a prominent role in Thursday’s hearing. In his deposition to the committee, Short said Pence had informed the president “many” times that he would not go along with the scheme.

Pence “never budged” from his initial view that the founding fathers would not have left it to one person to determine the outcome of a presidential election, and certainly not someone with such a significant stake in the outcome as a vice-president, Jacob testified.

The hearing concluded ominously, with a warning from Luttig that the same forces continue to threaten American democracy.

Trump and his allies remain “clear and present danger to American democracy,” Luttig told the panel, not because of what happened on January 6 but because of their determination to “succeed in 2024 where they failed in 2020”.