United States President Joe Biden has officially launched his campaign for re-election in 2024, becoming the Democratic frontrunner in a race that could pit him for a second time against Republican contender Donald Trump.

Biden’s announcement in a video on Tuesday came on the fourth anniversary of the start of his first successful presidential bid.

A majority of Democrats would back Biden, 80, against a Republican challenger in next year’s election, a recent poll found.

But the Democratic president faces some of the lowest approval ratings of his tenure so far, and his age – Biden is currently the oldest person to ever hold the highest US office – has spurred questions about his re-election prospects.

Biden, who would be 86 at the end of a second term, is betting his first-term legislative achievements and more than 50 years of experience in Washington will count for more than concerns over his age. He faces a smooth path to winning his party’s nomination with no serious Democratic rivals. But he is still set for a hard-fought struggle to retain the presidency in a bitterly divided nation.

“I said we are in a battle for the soul of America, and we still are,” Biden said in his campaign video. “The question we are facing is whether in the years ahead we have more freedom or less freedom, more rights or fewer.”

The Republican Party reacted to Biden’s announcement by calling the Democrat “out of touch”.

“Biden is so out of touch that after creating crisis after crisis, he thinks he deserves another four years,” the Republican National Committee said in a statement.

“If voters let Biden ‘finish the job’, inflation will continue to skyrocket, crime rates will rise, more fentanyl will cross our open borders, children will continue to be left behind, and American families will be worse off,” it said.

‘MAGA extremists’

Few things have unified Democratic voters as much as the prospect of Trump returning to power. And Biden’s political standing within his party stabilised after Democrats notched a stronger-than-expected performance in last year’s midterm elections. He set out to run again on the same themes that buoyed his party in November’s voting, particularly on preserving access to abortion.

“Personal freedom is fundamental to who we are as Americans. There’s nothing more important. Nothing more sacred,” Biden said in the launch video, which painted the Republican Party as trying to roll back access to abortion, cut Social Security pension benefits, limit voting rights and ban books it disagrees with.

“Around the country, MAGA [Make America Great Again] extremists are lining up to take those bedrock freedoms away,” Biden charged, referring to a Trump campaign slogan and his supporters. “This is not a time to be complacent. That’s why I’m running for re-election.”

Biden is facing a couple of long-shot primary challengers – including self-help guru Marianne Williamson and anti-vaccine activist Robert Kennedy Jr – but as a sitting president, he comes into the race for the Democratic nomination as a clear frontrunner.

The nominee will be confirmed at the party’s national convention in Chicago in August 2024.

Trump-Biden rematch?

On the Republican side, Trump is widely considered to be the 2024 frontrunner.

The former president announced his campaign in November, but since then, he has faced a series of legal woes, including criminal charges in New York over alleged hush-money payments he made to adult film star Stormy Daniels.

Still, Trump, who has pleaded not guilty in the case, maintains strong support with an NBC News poll finding this month that 46 percent of Republican primary voters would support him.

Florida Governor Ron DeSantis had the second-highest level of Republican support at 31 percent although he has yet to formally announce his candidacy.

Should Trump gain the Republican nomination, it would set Biden up for a rematch of the hard-fought 2020 election, which he won thanks to victories in key swing states.

In a statement about Biden’s candidacy, Trump criticised the president over his record on immigration, inflation, and the US pullout from Afghanistan.

“American families are being decimated by the worst inflation in half a century. Banks are failing,” Trump said on his social media platform. “We have surrendered our energy independence, just like we surrendered in Afghanistan.”