Efforts to hold Donald Trump criminally responsible for attempting to overturn the 2020 election are gaining steam, as the former US president prepares to face federal charges in a Washington courtroom on Thursday.

Trump – the front-runner for the 2024 Republican presidential nomination – was indicted on Tuesday on four counts, including conspiring to defraud the US, obstructing an official proceeding and conspiring to deprive voters of their right to fair elections.

In the 45-page indictment filed by Special Counsel Jack Smith, prosecutors described a sprawling, multi-state conspiracy built upon Trump's repeated false claims that Democrat Joe Biden's victory had been marred by widespread fraud.

According to the indictment, Trump ignored advisers who told him the election was not fraudulent and helped organize fake slates of electors to try to capture electoral votes in states he had lost.

Trump and his allies knowingly pushed those lies as part of a pressure campaign to try to convince state and federal officials to throw out the election results, prosecutors said, culminating in a mob of Trump supporters storming the US Capitol on January 6, 2021, in an attempt to block Congress from certifying Biden's victory.

"Despite having lost, the defendant was determined to remain in power," the indictment said.

Mike Pence and Donald Trump. – file

The Trump campaign issued a statement accusing the Biden administration of targeting him for political gain.

"The lawlessness of these persecutions of President Trump and his supporters is reminiscent of Nazi Germany in the 1930s, the former Soviet Union, and other authoritarian, dictatorial regimes," the campaign said.

Smith, the former chief prosecutor for the special court in The Hague, was appointed as special counsel by US Attorney General Merrick Garland. Special counsels are sometimes named to handle politically sensitive investigations to insulate the Justice Department from allegations of bias.

Trump, 77, the first former US president to face criminal charges, has been indicted on three separate occasions this year. In June, Smith's office charged him in a separate case with illegally retaining classified documents after leaving the White House and obstructing efforts to retrieve them.

Earlier this year, the Manhattan district attorney's office brought charges that he falsified business records to hide hush money payments.

Trump has pleaded not guilty in both cases and has portrayed those investigations, as well as the election probes, as part of a coordinated "witch hunt."

Special counsel Jack Smith speaks to the media about an indictment of former President Donald Trump. – AP

In Georgia, the district attorney in Atlanta, Fani Willis, has been investigating whether Trump and his associates illegally interfered with that state's election for more than two years. Willis, an elected Democrat, has signaled she intends to bring charges in that probe within the next three weeks.

Despite the steady drumbeat of scandal, Trump has continued to hold a wide lead over a field of Republican rivals in the 2024 presidential race, according to public polls.

Strategists said that while the indictments could help Trump solidify support among Republican voters, who view the charges as bogus, they could prove more damaging among independent voters in the general election against Biden.

Many Republican officials, unwilling to anger Trump's substantial base of supporters, attacked Biden instead, claiming that the latest charges were politically motivated.

Trump's chief rival for the Republican nomination, Florida Governor Ron DeSantis, declined to address the specifics in the indictment but vowed to end "the weaponization of the federal government."

Reactions from congressional leaders fall along partisan lines

Democratic Senate Majority Leader Chuck Schumer and House Minority Leader Hakeem Jeffries have called the January 6, 2021, riot at the US Capitol “one of the saddest and most infamous days in American history, personally orchestrated by Donald Trump and fuelled by his insidious Big Lie”.

But scores of Trump’s Republican allies in Congress criticised the indictment and its timing.

House Speaker Kevin McCarthy took to social media to comment about congressional testimony from a former business associate of Hunter Biden as Republicans look to connect President Joe Biden to his son’s business dealings and flirt with a potential impeachment inquiry against him.

“Everyone in America could see what was going to come next: DOJ’s attempt to distract from the news and attack the frontrunner for the Republican nomination, President Trump,” McCarthy said in a post on the social platform X, formerly known as Twitter.

Rioters loyal to President Donald Trump rally at the US Capitol in Washington on January 6, 2021. – AP

Elise Stefanik of New York, the third-ranking House Republican, called the indictment “an illegal attempt to interfere in the 2024 election”.

Senate Minority Leader Mitch McConnell, who delivered a blistering speech two years ago blaming Trump for January 6 right after he voted to acquit Trump in a related impeachment trial, made no public comment.

Mixed reactions from Trump's 2024 GOP rivals 

Trump’s rivals for the 2024 Republican presidential nomination have given mixed reactions to the latest indictment filed against him.

Florida Governor Ron DeSantis, his closest rival, did not defend Trump. But DeSantis said in a post Tuesday on the X platform, formerly known as Twitter, that he would “end weaponization of government, replace the FBI Director, and ensure a single standard of justice for all Americans” if elected president.

Former Texas congressman Will Hurd and former Arkansas Governor Asa Hutchinson, two of Trump’s most vocal critics in the field, issued statements saying Trump should not be the next US president.

Trump’s “denial of the 2020 election results and actions on January 6 show he’s unfit for office”, Hurd said in a post on X.

Hutchinson said in a statement that Trump “is morally responsible for the attack on our democracy", and should end his presidential campaign “for the good of the country”.

Trump received a staunch defence from biotech entrepreneur Vivek Ramaswamy, who has campaigned as someone ideologically aligned with Trump and even promised to pardon him should he win the White House.

Ramaswamy said Trump “isn’t the real cause for what happened on Jan 6” but instead blamed the riot on “systematic and pervasive censorship of citizens”.

People attend a rally in support of President Donald Trump on January 6, 2021, in Washington. – AP