The former president took to the stage at the Lincoln Day Dinner with his main rival Ron DeSantis and several other candidates in the race to become the party's nominee in 2024.

While his competitors broadly refused to speak about Mr Trump's ongoing legal problems, the former president made one veiled reference, saying: "If I weren't running, I would have nobody coming after me."

He also insisted the same would be true if he were trailing in the polls.

The other Republican candidates mostly reserved their sharpest criticism for Mr Biden and a Democratic party they argued had lost touch with mainstream America.

"The time for excuses is over. We must get the job done," Mr DeSantis told around 1,200 Republican party members and activists.

"I will get the job done," he said.

The Florida governor also repeated his promise to halt the "weaponisation" of the Justice Department, alluding to Mr Trump's indictments.

Mr Trump, who has a comfortable lead in the polls, was heavily critical of his rivals. He repeatedly branded Mr DeSantis "DeSanctus" and said: "I wouldn't take a chance on that one."

As he opened a campaign office outside Iowa's capital Des Moines before the dinner, Mr Trump said: "I understand the other candidates are falling very flat... it's like death."

Read more:
Donald Trump countersues woman jury says he sexually abused
Former president 'notified he is target' of investigation into attempts to overturn 2020 election
Trump widens lead over Republican rival despite legal woes, poll shows

Mr Trump frequently avoids attending events involving other candidates, questioning why he would share a stage with competitors who are trailing him in polls.

While most Republican candidates refused to criticise him, former Arkansas governor Asa Hutchison said, "as a party, we need a new direction for America and for the GOP", drawing only muted reaction from the crowd.

Will Hurd, a former Texas congressman, faced loud boos when he said: "The reason Donald Trump lost the election in 2020 is he failed to grow the GOP brand.

"Donald Trump is not running for president to make America great again... Donald Trump is running to stay out of prison."

Click to subscribe to the Sky News Daily wherever you get your podcasts

Iowa's caucus, one of the first contests in the race for the Republican nomination, is set to take place in January 2024.

Trump is facing several criminal and civil investigations and has been indicted twice.

On Friday, federal documents said he faced new charges over classified documents he allegedly took from the White House, including deleting CCTV footage of his staff moving boxes at his Florida home.

A trial in that case has been set to start on 20 May 2024 - just weeks before the Republican and Democratic national conventions where each party's nominees are set to be announced.