The House select committee investigating the January 6 insurrection on Monday scrutinized the conspiracy theories that led a group of Donald Trump’s supporters to attack the US Capitol and produced damning testimony for the former US president.

Over the course of the two-hour hearing, committee members meticulously documented how several of Trump’s senior advisers urged him not to declare victory on election night, as votes were still being counted.

When Trump began spreading lies about widespread fraud in the election, some of his top aides, including ex-attorney general and former Trump loyalist William Barr, repeatedly told him that the claims were baseless.

“We’ll tell the story of how Donald Trump lost an election and knew he lost an election and, as a result of his loss, decided to wage an attack on our democracy,” the Democratic chair of the committee, Mississippi congressman Bennie Thompson, said on Monday.

The committee had hoped that Bill Stepien, Trump’s former campaign manager, would testify in person on Monday, but he was unable to attend because his wife had gone into labor. Instead, Stepien’s attorney, Kevin Marino, appeared on his behalf.

The committee relied on previously recorded testimony from Stepien and other Trump allies – including his eldest daughter and senior adviser, Ivanka Trump, and his campaign attorney Rudy Giuliani – to show that the former president was told repeatedly on election night that he did not have the numbers to win.

The Wyoming congresswoman Liz Cheney, the Republican vice-chair of the committee, said Trump rejected several advisers’ guidance to wait for more votes to be counted on election night. Trump instead followed the advice of an “apparently inebriated” Giuliani to falsely declare victory before a winner was known, Cheney said at the Monday hearing.

Chris Stirewalt, a former political editor for Fox News, testified that Trump had no basis to declare victory on election night. Stirewalt boasted of his team’s decision to call Arizona for Joe Biden on election night, even though it later cost him his job (something Fox denies). Once Trump lost Arizona, Stirewalt said, his odds of winning the election were virtually nonexistent.

Facing the reality of his defeat, Trump chose to peddle baseless claims of widespread fraud in the election. In the days after the election, factions developed within the Trump campaign, as some aides backed Giuliani and his lies about the election while others supported Stepien and his pleas for reason.

“We called them kind of my team and Rudy’s team,” Stepien said in his recorded testimony. “I didn’t mind being categorized as ‘Team Normal’.”

Barr, who participated in a closed-door interview with investigators earlier this month, repeatedly tried to convince the former president that the election had been secure.

“I told him that the stuff that his people were shuttling out to the public was bullshit,” Barr said in a clip shared by the committee. “I was somewhat demoralized, because I thought, boy, if he really believes this stuff … he’s become detached from reality.”

According to Barr, Trump became “indignant” when his lies about the election were contradicted. “The president was as mad as I’ve ever seen him, and he was trying to control himself,” Barr said. “The president said, ‘Well, this is, you know, killing me. You didn’t have to say this. You must’ve said this because you hate Trump.’”

Trump had an obligation to make court challenges if he believed there was fraud, Thompson said, and also accept the decisions of the courts – he lost virtually every case – but he instead chose to attack the “rule of law”.

“He didn’t have the numbers. He went to court. He still didn’t have the numbers. He lost,” Thompson said. “But he betrayed the trust of the American people. He ignored the will of the voters.”

Select committee member Zoe Lofgren also showed how Trump and the Republican political apparatus used those baseless claims of fraud to rake in millions of dollars from unsuspecting Americans in fundraising, and how the Capitol attack was fueled by those claims perpetuated by Trump.

Between election day and the January 6 attack, the Trump campaign sent millions of fundraising emails, encouraging supporters to donate to the “Election Defense Fund”. One former campaign aide described that fund as a “marketing tactic”, sparking accusations from Lofgren that Trump and his team had misled donors. The last fundraising email was sent just 30 minutes before the Capitol was breached, Lofgren noted.

“The big lie was also a big ripoff,” Lofgren said.

The hearing on Monday, which saw Lofgren take a lead role in questioning witnesses instead of committee counsel, comes four days after the panel held its first hearing in prime time.

At that first session, the select committee featured shocking and at times emotional testimony from key witnesses who have spoken to investigators over the past year as they conducted the first stage of their inquiry behind closed doors in Washington.

Members of Trump’s inner circle testified that the former president was repeatedly told his claims of widespread fraud in the 2020 election that deprived him of victory over Biden were entirely baseless, but he continued to spread those lies in the weeks leading up to the insurrection.

Last week’s hearing laid the groundwork for the committee’s argument that Trump played a central role in the planning of the insurrection and bears personal responsibility for the deadly attack. A mob overran the US Capitol on January 6 last year, the day that Congress was due to officially certify Biden’s win over Trump in the previous November’s presidential election.

The four remaining hearings are expected to build upon that argument, as committee members attempt to present a meticulous case for Trump’s culpability.

“Over multiple months, Donald Trump oversaw and coordinated a sophisticated seven-part plan to overturn the presidential election and prevent the transfer of presidential power,” Cheney said on Thursday. “In our hearings, you will see evidence of each element of this plan.”

The Monday hearing provided committee members with another opportunity to convince the country that America’s democracy is facing a threat from those who do not believe in free and fair election.

The panel has accused Trump and his associates of having engaged in a “criminal conspiracy” and argues that the former president bears personal responsibility for the deadly attack on the US Capitol.

Although Trump was impeached by the House for inciting the insurrection, he was acquitted by the Senate, leaving many of his critics feeling as though he was not held accountable for his actions.

If the committee is successful in building its case against Trump, the hearings could deliver a devastating blow to the former president’s hopes of making a political comeback in the 2024 presidential election. But if Americans are unmoved by the committee’s findings, the country faces the specter of another attempted coup, Thompson warned.

“It all comes down to the numbers,” Thompson said on Monday. “The very least we should expect from any person seeking a position of public trust is the acceptance of the will of the people: win or lose.”

Hugo Lowell contributed to this report