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.