“He sees January 6 as a tragic culmination of what those four years under President Trump did to our country” and will “forcibly push back on the lie spread by the former president in an attempt to mislead the American people”.

Asked if Biden would use Trump’s name, Psaki said “we’re finalising the speech, but I think people will know whom he’s referring to”.

Earlier on Wednesday, the Capitol police chief, Thomas Manger, said his forces would not be caught unprepared again, as they were last year.

“I am confident that the US Capitol Police is a stronger, better prepared law enforcement agency,” Manger told a Senate hearing, recalling the desperate struggle his officers put up against “a violent mob and vastly outnumbered”.

Trump cancels Capitol riot anniversary press conference

Attorney General Merrick Garland was also to spell out efforts to “hold accountable those responsible” for the mayhem and underline law enforcement’s “unwavering commitment to defend Americans and American democracy”, the Justice Department said.

However, in the political sphere, the country remains dangerously divided.

Underlining the stunning partisan split, senior Republicans appear set to skip commemorations organised by the Democratic-led Congress on Thursday, including Biden’s speech and a prayer vigil.

Senate Republican leader Mitch McConnell was set to be away in Atlanta, Georgia, attending the funeral of the late senator Johnny Isakson, his office said.

In an opinion piece on Fox News, Republican Senator Josh Hawley, a leading supporter of false claims that Biden’s 2020 victory was suspect, referred to January 6 as a “demonstration” that “some demonstrators” marred.

“Gathering for a political demonstration is not a crime. On the contrary, it is a right expressly protected by the US Constitution,” he wrote.

Trump himself continues to push the lie that the 2020 election was stolen by Biden – a conspiracy theory dismantled in multiple court findings and vote recounts.

He had been planning a press conference at his Florida home to steal the limelight on Thursday, but abruptly abandoned the plan in a statement Tuesday that nevertheless continued to claim that the 2020 election was a “crime”.

Twitter on alert for calls to violence on US Capitol attack anniversary

In his testimony, Manger paid tribute to his badly prepared officers as they tried to face down angry Trump supporters, who poured over police barricades, smashed windows to get into the Capitol, vandalising offices and the chamber itself.

For hours as the struggle unfolded, lawmakers fled to safety or hid behind barricaded doors. Trump’s vice-president Mike Pence, who was in the Capitol to preside over the certification of Biden’s win, fled as attackers chanted “hang Mike Pence”.

“Their eyes inflamed by repeated shots of pepper and bear spray, their bodies assaulted and beaten with bricks, flag poles, rebar, pipes, bats, sticks, tasers, among other weapons, they fought for over four hours,” Manger said.

“Fighting hand-to-hand, using ingenuity and displaying incredible grit, they did not give up. Congress was able to do its job and not one Member, or staff, was physically harmed.”

Democratic Senate Majority Leader Chuck Schumer recalled on Wednesday how a police officer had grabbed him during the unrest and told him they were “in danger”.

“I was within 30 feet (nine metres) of these nasty insurrectionists,” Schumer said, describing the attack as an attempt to reverse “the outcome of a free and fair election”.

“Without addressing the root causes of the violence on January 6, the insurrection will not be an aberration it could well become the norm,” he warned.