Donald Trump has used his first campaign event since President Joe Biden officially entered the 2024 election race to portray their differences in stark and apocalyptic terms, arguing a Biden re-election would lead to "anarchy" and portraying Biden as senile and lacking energy in a mocking moment.

Speaking to more than 1,000 supporters on Thursday, many wearing red "Make America Great Again" hats, the former US president sought to reframe the choice between the two men.

Biden, a Democrat, launched his re-election campaign two days ago with a video promising to protect personal freedoms from "extremists" linked to the former Republican president.

"The choice in this election is now between strength or weakness, between success or failure, between safety or anarchy, between peace or conflict, and prosperity or catastrophe," Trump said in a speech in Manchester, New Hampshire.

"With your vote on November 5th, 2024, we are going to crush Joe Biden."

Trump's remarks assume that both he and Biden will win their party's nominations.

Trump appeared to be consolidating his support in the race for the Republican nomination and travels to New Hampshire in the hope of capturing the early nominating state.

Trump had a sizeable national lead over Florida Governor Ron DeSantis, 49 percent to 23 percent, among self-identified Republicans, according to a Reuters/Ipsos poll conducted April 21-24.

Benefiting from a large field of candidates and tapping into the angst of working-class voters, Trump handily won New Hampshire's primary in 2016 in a prelude to victories across the Northeast and ultimately the Republican nomination.

In a mocking moment, Trump drew applause when he shuffled around the stage pretending he was struggling to find the exit, suggesting he may revive a theme from his 2020 campaign when he portrayed Biden as frail and lacking mental acuity.

"Biden announced his presidential campaign by, get this, a prepackaged video. I was going to do that for you today. I'll do a little video, send that up to New Hampshire, you wouldn't have been very happy about that," Trump said.

"But when you're running for president, you'd think at least one time he'd get up and say, 'I'm running for president? Where? Where am I going? Where the hell am I going? I want to get out. Oh, no. Over there. Over there'."

'Trump is a loser'

Many top Republicans say Trump, 76, is positioning himself to lose again after leading Republicans to poor showings in the 2020 general election and in the last two midterm cycles.

"Republicans want someone who can win in November of '24. Donald Trump is a loser," New Hampshire Governor Chris Sununu, who is said to be mulling a rival presidential bid, told NBC on Sunday.

Nine Republicans in the US Senate have endorsed the billionaire, but others warn that prosecutions enmeshing Trump might undermine their hopes of taking the upper chamber of Congress back from the Democrats next year.

Trump is being sued for battery and defamation in civil proceedings in New York, accused of raping writer E Jean Carroll in 1996, and has been indicted over a 2016 hush money payment to an adult actress in a criminal case likely to stretch well into the election year.

He also faces the possibility of charges from the Department of Justice and Georgia prosecutors in cases involving his attempts to overthrow the 2020 election and his hoarding of government documents.

Trump, who denies all wrongdoing, angrily denounced the "endless witch hunts" against him, as he invariably does in public remarks, and told supporters he was retiring the "Crooked" nickname he uses to smear longtime foe Hillary Clinton and giving it to Biden instead.