Members of right-wing militia groups and other supporters of Donald Trump staged the January 6, 2021 assault on the US Capitol after a tweet from the former president seen as a "call to arms," lawmakers said Tuesday.

Representative Liz Cheney, vice chair of the House committee investigating the attack on Congress, meanwhile said that the 76-year-old Trump had recently attempted to contact a committee witness.

The House committee investigating the January 6, 2021 attack on the US Capitol is to hold its seventh hearing
The House committee investigating the January 6, 2021 attack on the US Capitol is to hold its seventh hearing AFP / OLIVIER DOULIERY

The witness, who was not identified, did not take the call from Trump and alerted their lawyer, Cheney said, adding that the committee has "supplied that information to the Department of Justice."

During its seventh televised public hearing, the House committee made up of seven Democrats and two Republicans examined the impact of a tweet that Trump sent on December 19, 2020 urging his supporters to descend on Washington on January 6 for a rally he promised would be "wild."

Trump supporters clash with police on January 6, 2021 at the US Capitol
Trump supporters clash with police on January 6, 2021 at the US Capitol AFP / Olivier DOULIERY

The tweet was sent a little more than an hour after Trump met at the White House with his lawyer Rudy Giuliani, former general Mike Flynn, and Sidney Powell, another attorney, for a strategy meeting that one aide described as "unhinged."

Committee member Jamie Raskin said that Trump's "1:42 am tweet electrified and galvanized his supporters, especially the dangerous extremists in the Oath Keepers, the Proud Boys and other racist and white nationalist groups spoiling for a fight against the government."

Members of the Proud Boys and the Oath Keepers stormed Congress on January 6 along with thousands of other Trump loyalists in an attempt to block certification of Democrat Joe Biden's presidential election victory, which Trump falsely claims was marred by fraud.

US Representative Jamie Raskin (R) and Representative Liz Cheney (L) during a hearing of the House select committee investigatin the January 6, 2021 attack on the US Capitol by Trump supporters
US Representative Jamie Raskin (R) and Representative Liz Cheney (L) during a hearing of the House select committee investigatin the January 6, 2021 attack on the US Capitol by Trump supporters AFP / SAUL LOEB

Representative Stephanie Murphy, another committee member, said the tweet "served as a call to action, and in some cases as a call to arms, for many of president Trump's most loyal supporters."

The committee said two of Trump's closest backers, Flynn and political consultant Roger Stone, had connections to the Oath Keepers.

Jason Van Tatenhove, a former spokesman for the Oath Keepers, testifying before the House committee investigating the January 6, 2021 attack on the US Capitol
Jason Van Tatenhove, a former spokesman for the Oath Keepers, testifying before the House committee investigating the January 6, 2021 attack on the US Capitol GETTY IMAGES via AFP / Anna Moneymaker
Stephen Ayres (C), who entered the US Capitol illegally on January 6, 2021, greets former Washington police officer Michael Fanone, who was injured during the attack on  Congress
Stephen Ayres (C), who entered the US Capitol illegally on January 6, 2021, greets former Washington police officer Michael Fanone, who was injured during the attack on Congress GETTY IMAGES via AFP / Kevin Dietsch

The committee also said the march to the Capitol was planned in advance but that Trump decided not to announce it until the speech he made to supporters on the morning of January 6 near the White House.

"The evidence confirms that this was not a spontaneous call to action, but rather was a deliberate strategy decided upon in advance by the president," Murphy said.

Cassidy Hutchinson, an aide to Trump's chief of staff Mark Meadows, testified at a previous hearing that the president had intended to go to the Capitol himself but was prevented from doing so by Secret Service agents.

An image of former US president Donald Trump is shown during a committee hearing into the January 6, 2021 storming of the US Capitol
An image of former US president Donald Trump is shown during a committee hearing into the January 6, 2021 storming of the US Capitol AFP / SAUL LOEB

The committee is trying to determine whether Trump or his associates had a role in planning or encouraging the violent insurrection and has subpoenaed numerous advisors and aides to the former president.

It played the first videotaped excerpts on Tuesday from closed-door testimony last week by former White House counsel Pat Cipollone.

In his testimony, Cipollone said he agreed there was no evidence of significant election fraud and that Trump should have conceded to Biden.

The committee also heard from two witnesses, Jason Van Tatenhove, a former spokesman for the Oath Keepers, and Stephen Ayres, an Ohio man who joined the mob storming the Capitol.

Van Tatenhove said the Oath Keepers were a "dangerous organization" who believed their allegiance to Trump would give them "legitimacy" as a paramilitary outfit.

Ayres told the committee that he came to Washington because "the president got everybody riled up," but that he no longer believed his claims that the election was "stolen."

More than 850 people have been arrested in connection with the attack on Congress.

Five members of the Proud Boys were indicted in June on seditious conspiracy charges and 11 members of the Oath Keepers face the same charges, which carry a sentence of up to 20 years in prison.

The assault on the Capitol left at least five people dead and 140 police officers injured.

Trump was impeached for a historic second time by the House of Representatives after the riot -- he was charged with inciting an insurrection -- but was acquitted by the Senate.

In a statement Tuesday on the Truth Social platform, Trump, who has been hinting at running for the White House again in 2024, denounced the committee as "Political Hacks and Thugs."

"Have you seen them before?" he asked. "Yes, they are essentially the same lunatics that drove the Country 'crazy' with their lies and made up stories."