Former UN Ambassador Nikki Haley campaigns across New Hampshire on Monday hoping to stall Donald Trump's march to the 2024 Republican presidential nomination with an upset victory in the state's primary vote on Tuesday.

Eight days after Trump coasted to a record-setting win in Iowa's first-in-the-nation contest, the former president is aiming to deliver a fatal blow to Haley's upstart campaign by notching another commanding victory.

The race was transformed into a one-on-one battle on Sunday, when Florida Governor Ron DeSantis ended his struggling campaign after he and Haley jockeyed to emerge as the leading Trump alternative. All other major candidates dropped out after Iowa.

For Haley, New Hampshire represents perhaps her final chance to prove the Republican base could consider someone other than Trump, who has rallied the party's faithful despite facing 91 felony counts. He has pleaded not guilty to every crime, claiming he is the victim of political persecution.

Haley is holding five campaign events on Monday, finishing with an evening rally in Salem, a suburb of Boston. Trump is having just one event, a 9 p.m. ET rally in the central town of Laconia.

The state's large number of independent voters, who are permitted to cast ballots in Tuesday's election, make New Hampshire friendlier turf for Haley than more conservative Iowa.

Even so, Trump holds a double-digit lead in most statewide public polls. While DeSantis had only around 6% support, he endorsed Trump upon leaving the race on Sunday, and his backers are more likely to transfer their allegiance to Trump, according to pollsters.

A Haley victory could give her campaign the momentum - and fundraising - it needs ahead of the next nominating contest on Feb. 24 in South Carolina, her home state where she served two terms as governor. A Trump victory, meanwhile, would add to the air of inevitability he has sought to create around his candidacy.

Trump has won the endorsement of lawmakers from Haley's home state including Senator Tim Scott, who had campaigned for the nomination. On Monday, Nancy Mace, another South Carolina lawmaker, endorsed Trump and said it was time "to unite behind our nominee."

Haley won the endorsement on Monday of former Arkansas Governor Asa Hutchinson, a Trump critic who staged a presidential campaign but dropped out after struggling to gain traction.

The winner of this year's Republican nominating contests will take on President Joe Biden, the presumptive Democratic nominee, in November's general election.

While the Republican rivals campaign in New Hampshire, Biden and Vice President Kamala Harris will kick off a series of events intended to highlight Republican-backed limits on abortion that Democrats generally oppose.

Monday is the 51st anniversary of Roe v. Wade, the decision that established a nationwide right to abortion until the US Supreme Court reversed it in 2022, galvanizing Democratic voters.

Trump to attend trial

Trump had been expected to spend the morning and potentially testify in a New York courtroom in a defamation case brought against him by author E. Jean Carroll, who says he raped her decades ago. Trump accuses Carroll of making up the story to boost her memoir.

But the trial was postponed to Tuesday after a juror reported feeling ill and a parent of Trump's lead lawyer tested positive for COVID-19. The judge in the trial said he will decide later whether to let Trump testify on Wednesday, so he can be in New Hampshire for Tuesday's vote.

As with his criminal cases, which he has frequently used in fundraising pleas, Trump has portrayed the E. Jean Carroll case as part of a broader conspiracy by liberal forces to derail his candidacy.

A separate jury last May found Trump civilly liable for sexually abusing Carroll and ordered him to pay $5 million in damages, a result Trump called a "disgrace."

In recent days, Haley, 52, has intensified her attacks on Trump, asserting the 77-year-old has suffered some cognitive decline since his time in the White House and criticizing him for embracing authoritarian foreign leaders.

At a rally on Sunday in Rochester, New Hampshire, Trump accused Haley of relying on an "unholy alliance" of liberals, 'never-Trumpers' who oppose him and RINOs, or Republicans in Name Only. He has used a version of her given first name, Nimarata, as an insult and amplified false posts on social media questioning her birthright US citizenship.

Haley is the daughter of Indian immigrants and was born in South Carolina.