ATKINSON, United States, Jan 17, 2024 (BSS/AFP) - Donald Trump steamrolled into New Hampshire Tuesday after his crushing win in Iowa cemented him as the likely Republican presidential nominee -- stopping on the way for a defamation trial that underscores how much the road to November's election remains in uncharted territory.

The twice-impeached former president romped home in the first contest of the drawn-out 2024 race for the White House, scoring 51 percent of Republican voters to trounce rivals Ron DeSantis and Nikki Haley for the biggest Iowa caucus victory in modern history.

Victory in next Tuesday's New Hampshire primary would mean Trump, 77, could all but seal the nomination -- and a grudge rematch against President Joe Biden -- as he aims for a sensational White House comeback despite a string of scandals that would sink most other politicians.

Before heading to the New England state, though, Trump had another appointment, appearing in a New York courtroom where he is on trial for defamation in the wake of a jury finding he was liable for a 1990s sexual assault against writer E. Jean Carroll.

Trump has used the Carroll case, and 91 criminal indictments on allegations including his bid to overturn the 2020 loss to Biden, to galvanize Republican supporters with his claims of a "deep state" trying to keep him out of power.

While Trump's victory speech in a wintry Iowa at first struck an unusually conciliatory note -- saying it was "time now for everybody, the country, to come together" -- he soon reverted to the harsh rhetoric that promises one of the most divisive elections in memory.

He vowed to shut the Mexican border to stop an "invasion" of migrants, and hammered home the abrasive messaging that has fired up his base as he seeks what he says will be "retribution" against Democrat Biden.

For his part, Biden sought to reassure his supporters that Trump's strong showing in Iowa was not cause for alarm.

"I am still the only person to ever beat Donald Trump and I am looking forward to doing it again -- for the good of this country," he said in a video posted on X, formerly Twitter.

- 'Impressive' -

As snow piled up in Atkinson, some 40 miles (65 kilometers) from New Hampshire capital Concord, hundreds of Trump supporters gathered for the ex-president's latest campaign stop Tuesday.

"I expect a landslide in the primary," Loribeth Calderwood, a waitress, told AFP while waiting in line, covered head-to-toe in a blanket to keep warm. "And if he doesn't, I think it's because they stole the election again."

"It's over, they should just stop the primary," said Edward X. Young, who drove 11 hours from New Jersey. "He's the Republican candidate... come on."

Florida Governor DeSantis and former UN ambassador Haley will also head to the East Coast state as they scramble to shore up their campaigns.

Ahead of Trump's arrival in New Hampshire, plumber Vern Aylward, 64, said he was "happily surprised" by the size of Trump's Iowa win.

"I think he proved himself when he was president," Aylward told AFP after parking his white pickup truck. "The gas, price of food, just seemed like everything was going swimmingly."

It's a familiar narrative for Trump supporters and a dangerous one for Biden, 81, who is neck-and-neck or behind the Republican in match-up polls, with voters particularly concerned about inflation.

But the message is working against Trump's Republican opponents too. In frozen Iowa, Trump opened an unprecedented 30-point gap over DeSantis, who had pinned his hopes on a strong showing, while Trump's former UN ambassador Haley was third with 19 percent.

The Republican field also narrowed, with biotech entrepreneur Vivek Ramaswamy dropping out and endorsing Trump on Monday night. Long-shot former Arkansas governor Asa Hutchinson -- the last Republican candidate to openly criticize Trump -- ended his campaign on Tuesday.

- 'Fear' -

Haley, who like DeSantis is portraying herself as a Trump alternative, said she would not join the next Republican debate ahead of the vote in New Hampshire, her preferred battleground, without Trump. Trump has so far refused to take part in any debates.

DeSantis is also heading to New Hampshire after a pitstop in South Carolina, seeking to deal an early blow to Haley, who was formerly governor there.

But while DeSantis confirmed that he would stay in the race to "reverse the madness," he is considered weak in New Hampshire and many analysts declared his campaign all but dead.

The US election is being watched around the world, with allies Ukraine and Israel embroiled in wars and many countries anxious about a return of Trump's "America First" policies.