The response from some of those GOP officials now? We didn't think it would come to this.

"People took him literally. I never thought I would see that," said Mick Mulvaney, Trump's former chief of staff. Mulvaney resigned his post as special envoy to Northern Ireland after the riots.

That argument reveals the extent to which many Republicans have willingly turned a blind eye throughout Trump's presidency to some of the forces coursing through America.

Each time Trump promoted a conspiracy theory or openly flirted with extremist groups, Republicans assumed there were still some limits to how far he and his most loyal supporters would go.

Few seemed concerned about the worst-case scenarios, dismissing fears of violence or authoritarianism as liberal fever dreams.

Pennsylvania Senator Pat Toomey, who backed Trump in the 2020 election but is now calling for him to resign, cast Trump's actions after his loss as a dark shift, despite the fact that the president laid the groundwork for challenging the election before the first votes were cast.

"He descended into a level of madness and engaged in a level of activity that was just absolutely unthinkable," Toomey said.

If some Republicans had reservations about Trump before the election, they often appeared to be overshadowed by their belief that there would be a political price to pay for openly challenging the president.

Even after Trump's loss to President-elect Joe Biden, GOP lawmakers worried about the hold he would have on their party in the coming years and the prospect of a primary challenge in their races if they crossed him.

Well aware of this reality, Trump tried to box Republicans in further by vowing to run again in 2024, even without conceding the 2020 election.

And so most GOP officials gave the president time and space to falsely attack the integrity of the November election, spread a vast array of misinformation and delegitimise Biden's victory in the eyes of millions of Americans.

Most privately acknowledged Biden's victory, but rationalised that the best way to help ease Trump out of office was to give him space to come to grips with his loss.

But that never came to pass. Even as judges across the country dismissed case after case and Attorney General William Barr, a Trump stalwart, said there was no sign of any widespread election malfeasance, the president kept up his baseless attacks.

Some Republicans were complicit in the falsehood with their silence, while others were active participants.

More than 120 GOP lawmakers asked the Supreme Court to overturn the will of the voters in key battleground states, an unprecedented step the high court refused to consider.

As late as Wednesday morning, 150 lawmakers in the House and Senate promised to object to the election results in Congress, helping fuel the impression among some Trump supporters there was still an avenue available for subverting Biden's victory.

But Utah Senator Mitt Romney, long a critic of the president and the only Republican senator who voted to convict Trump during his impeachment trial early last year, warned about the dangerous consequences of letting Trump's election conspiracies flourish.

So did Republican officials in Georgia, who withstood direct pressure from the president to "find" him more votes and overturn Biden's victory in the state.

Senate Majority Leader Mitch McConnell waited until mid-December to recognise Biden's victory, then aggressively warned his members against challenging the election results in Congress.

But for many Republicans, it was only on Wednesday, when their own lives were put at risk by the violent mob that stormed the Capitol, that the consequences of the president's dangerous disinformation campaign became clear.

"Count me out. Enough is enough," said South Carolina Senator Lindsey Graham, one of Trump's most ardent backers throughout the last four years.

Graham was later surrounded by angry Trump supporters at a Washington-area airport, who accused him of being a traitor to the cause of overturning the election.

Several senators who intended to object to the election results changed their minds in the hours after the insurrection, suggesting they had never believed in the fraud allegations in the first place.

Among them: Senator Kelly Loeffler of Georgia, who lost a Senate runoff two days before the riots. Loeffler had thrown her support behind the election objections in a last-minute bid to energise Trump backers in her state.

An AP VoteCast survey of the electorate in Georgia showed that about three-quarters of voters who backed Republican candidates in the runoffs said Biden was not legitimately elected.

Republicans must now contend with the reality that millions of their party's supporters believe a lie so powerful that it sparked an insurrection against Congress.

And within their own ranks, nearly 150 lawmakers still backed challenges to the election after Congress reconvened following the assault on the Capitol.

And while a vast majority - 88 per cent- of Americans oppose the rioters' actions, nearly a fifth of Republicans - 18 per cent - said they support them, according to a new PBS Newshour/Marist poll.

Australian Associated Press