Biden acknowledges Trump as GOP  presidential frontrunner after Iowa win

Donald Trump romped to a lightning-quick victory in Iowa's caucuses - the first vote in the US presidential race - cementing his status as the presumptive Republican standard-bearer to challenge President Joe Biden in November's election.

Democrat President Joe Biden acknowledged that Donald Trump was the "clear front runner" to be the Republican candidate in the US election after Trump won the Iowa caucuses.

"Looks like Donald Trump just won Iowa. He's the clear frontrunner on the other side at this point," Biden said on X, formerly Twitter.

The former president has led polling for more than a year, but Monday's contest was seen as the clearest insight yet into whether he can convert his advantage into a stunning White House return.

Major US networks took just 30 minutes to project the winner, with Trump opening up an unprecedented 32-point lead over second-placed Ron DeSant is over the following hour or so.

The Florida governor and Trump's other main rival - former UN ambassador Nikki Haley - appeared to be locked in a tussle for the runner-up spot at around 20 and 19 percent respectively.

There had been questions as to whether Trump might have been hamstrung by his legal problems, as he faces civil and criminal trials in multiple jurisdictions in 2024.

But the Iowa victory demonstrated the 77-year-old's success in turning his prosecutions into a rallying cry that has galvanised his followers as he takes his momentum into New Hampshire, the next state to nominate, next Tuesday.

Ramaswamy drops out

Meanwhile, Vivek Ramaswamy, a multi-millionaire former biotech executive, ended his White House bid and endorsed Donald Trump after his longshot bid caught attention but failed to catapult him high enough in the Republican Party's first nominating contest in Iowa.

Ramaswamy, a 38-year-old born in Ohio to immigrant parents from southern India, was one of the surprises of the 2024 Republican race dominated by former President Trump.

A fierce defender of Trump throughout the campaign, Ramaswamy likely secured himself a spot in Republican politics going forward with his youthful demeanour, deep pockets and fast-talking pugnacious campaigning.

However, Trump turned on him in the final days leading up to the Iowa caucus, calling him a "fraud" and asserting that a vote for Ramaswamy was a vote for the "other side."

Partial results for the Iowa caucuses showed Ramaswamy coming in fourth with around 7.7 percent of votes.