Laconia, New Hampshire - Donald Trump aims to steamroll his way toward the Republican presidential nomination Tuesday in the New Hampshire primary, making short work of his only surviving opponent, former UN ambassador Nikki Haley.

In his convention-smashing mission to take revenge against President Joe Biden and win a second White House term, Trump has defied the fallout from two impeachments, four criminal trials awaiting him, and lawsuits for fraud and sexual assault.

While Haley has questioned his mental fitness and warned that another Trump presidency would bring "chaos," polls indicate her candidacy will provide little more than a bump in the road in New Hampshire.

"If you want a losing candidate who puts America last, vote for Nikki Haley," Trump said in his closing arguments at a small but lively rally in the village of Laconia.

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"But if you want a president who puts America first every single time, you're going to vote for Donald J. Trump."

New Hampshire is seen as a more Haley-friendly electorate than any she will encounter further down the line and pressing on into February will be a tough sell without a win or very close defeat.

Trump (77) had a crushing victory in the first contest in Iowa last week – Haley was a distant third – and no Republican has ever won both opening contests and still fallen short.

The first place to vote in New Hampshire's primary, the tiny hamlet of Dixville Notch, handed all six ballots to former South Carolina Governor Haley.

Most of the state's remaining polling stations will open between 6:00 AM and 8:00 AM on Tuesday.

What was once a crowded field of 14 candidates narrowed to a one-on-one match-up after Florida Governor Ron DeSantis pulled the plug on his campaign on Sunday, after coming second in Iowa.

He and Trump were in a comparatively close race until the ex-president's indictments for accounting fraud, criminal election interference, and Espionage Act violations began to drop in March, compelling his supporters to close ranks.

Scott Manninen, a 48-year-old production manager in the manufacturing sector, told AFP at a campaign event in the village of Hollis on Monday that the legal issues would not stop him from voting for Trump.

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"I think it's a lot of smoke and mirrors – just trying to bash him and trying to get it so that people go against him," he said.

"I'm not worried about it. I think he's going to get through it."

Trump has spent less time in New Hampshire than Haley, juggling one rally a night with court appearances out of state – and eschewing the "retail politics" of visits to diners, sports halls, and high schools altogether.

But his message – a mixture of personal grievance and culture war issues that speak to his base – has delivered seemingly insurmountable polling leads nationwide.

A Globe/Suffolk/NBC10 poll had Haley 19 points behind in New Hampshire on the eve of the election.

One of Trump's biggest gripes on the campaign has been the false claim – repeated in Laconia – that Democrats are allowed to vote in the Republican contest.

Independents can have their say, however, and Haley is seeking to energize a flagging campaign with support from the famously moderate bloc, which outnumbers registered members of either party.

She has spent the week hammering home the message – backed by polling – that the majority of Americans do not want to see a Trump-Biden rematch in November.

Haley (52) told Fox News on the eve of the election she was in the race "for the long haul," adding: "This is a marathon, it's not a sprint."

New Hampshire Democrats are also voting for their standard-bearer on Tuesday, but Biden did not file candidate papers after a row with local officials over scheduling.

Some supporters have pledged to write his name on the ballot in hopes he can still beat Minnesota Congressman Dean Phillips and progressive challenger Marianne Williamson.