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.
This story is from the January 17, 2024 edition of Daily Express.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the January 17, 2024 edition of Daily Express.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber? Sign In
IDEAL TONIC FOR ARTETA
Bug-hit Gunners roar back as quick double floors Bees
Pickford loving good old days
JORDAN SAVOURS THE GOODISON FAREWELL
The 12-minute workout that keeps Dame Helen looking fabulous at 79
DAME Helen Mirren says people on a new year health kick needn't splurge on gyms - she still swears by a 12-minute daily routine at home.
WILSON'S A WINNER FOR BLACK CATS
Sunderland home in on top
Kop that! Bunting weaves his magic
TITLE GLORY AND ANFIELD IN SIGHT
RAI HAS 'GREAT' SHOT AT CALL-UP
Donald says Aaron is on f right track for Ryder Cup
HENDO FINDS A GOOD PLACE
LUCKY PLACE impressed with a Relkeel Hurdle triumph at Cheltenham - and is now 10-1 (from 25-1) for the Stayers' Hurdle at the National Hunt Festival in March.
After years of treating my body badly, I now treat it well
Dylan Simkin, 49, had been overweight since his 20s and had a liver transplant in 2021. But after the op he hit 19 stone, so the maths tutor, from Atherstone, Warks, turned to his local Slimming World for help
Can Gen Z's new noise trend bring me calm?
Lying on a hard dance floor with just a thin mat and cushion under my knees for comfort, my back cannot get comfy and my hair gets stuck in my headphones.
'My secret for a long life? Don't get married!'
Kath reflects on love of freedom as she turns 103