The former president vowed to "take America back" as he cemented his place as the party's frontrunner for November's election.
And the margin of victory put the US and the rest of the world on notice of how popular Trump remains with Republican voters.
It sets up a November 5 contest to be more explosive than Bonfire Night and fraught with complexities.
Both politicians would be the oldest president to win an election.
Biden, 81, who would be 86 by the time a second term finished, has been seen stumbling at events and committing several gaffes.
While Trump, no spring chicken at 77, has 91 criminal charges levelled against him.
But that did not appear to put off voters in Iowa on Monday as Trump saw off his closest rivals Ron DeSantis and Nikki Haley.
He won more than half of the votes in the state, confirming predictions he would begin his third presidential campaign with a telling victory.
In the lowest-turnout caucus in 25 years, voters had endured lifethreatening cold weather and dangerous driving conditions to meet in hundreds of schools, churches and community centres.
Those who ventured out delivered a roughly 30-point win for Trump that smashed the record for an Iowa Republican caucus and tightened Trump's grip on the party's nomination. However, it is still several months before the party's standard bearer can be confirmed.
Denne historien er fra January 17, 2024-utgaven av Daily Express.
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Denne historien er fra January 17, 2024-utgaven av Daily Express.
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We won't call it quits on blitz
HENRY STILL CONVINCED SYSTEM WILL TAME BOKS
JACOB BATS AWAY THE SUDDEN HYPE
Bethell keeps a level head after rapid England impact
Open wound still stings for Rory
'IT'S ONE THAT GOT AWAY'
First test looming for Lewis
NEW YEAR REVOLUTION
STRAIGHT AS A DY
O'Brien star will not lack for fitness
Pie heir 'killed his friend in planned Christmas attack'
THE heir to a £230million pie empire murdered his housemate by stabbing him in a planned Christmas Eve attack, a jury was told.
Shoplift gang's £200k haul of luxury goods
THREE shoplifters who plundered supermarkets and walked away with luxury goods, including champagne worth £4,500, have been jailed.
Church requires 'a hurricane of change' to clean up its act
DAME Vera Baird wants more senior clerics to quit or be fired over Church of England abuse revelations.
£1.4m payout for mum flung from fairground ride
A MOTHER who suffered serious injuries when she was hurled from a fairground ride has agreed a £1.43million settlement.
Give Beeb's overpaid nonentities red card
IN AN increasingly bleak world, a piece of unmitigated good news is exceedingly welcome and here it is: Gary Lineker is stepping down from Match Of The Day.
