Donald Trump won New Hampshire's Republican presidential primary election on Tuesday, Edison Research projected, further asserting his dominance over the party as he heads toward a likely November rematch with Democratic President Joe Biden.
But his only remaining rival, former UN Ambassador Nikki Haley, told her supporters at a primary night party in Concord: "This race is far from over." She congratulated Trump but added vowed to fight and challenged him to debate her.
With 16 per cent of the expected vote tallied, according to Edison, Trump had 53.2 per cent compared with 45.3 per cent for Haley, who had hoped the Northeastern state's sizable cadre of independent voters would carry her to an upset win that might loosen Trump's iron grip on the Republican Party.
Instead, Trump will become the first Republican to sweep competitive votes in both Iowa - where he won by a record-setting margin eight days ago - and New Hampshire since 1976, when the two states cemented their status as the first nominating contests.
While the final margin was still unclear, the results will likely increase calls from some Republicans for Haley to drop out of the race, though her campaign vowed in a memo on Tuesday to push forward until "Super Tuesday" in early March, when Republicans in 15 states and one territory vote on the same day.
The next contest is scheduled for February 24 in South Carolina, where Haley was born and served two terms as governor. Despite her ties, however, Trump has racked up endorsements from most of the state's Republican figures, and opinion polls show him with a wide lead.
Haley finished third in Iowa, just behind Florida Governor Ron DeSantis, while focusing much of her early campaign on New Hampshire, where the more moderate electorate was expected to offer perhaps her best chance of winning a state over Trump.
New Hampshire was the first contest to feature a one-on-one matchup between Trump and Haley, after Florida Governor Ron DeSantis, once seen as Trump's most formidable challenger, dropped out on Sunday and endorsed Trump.
Despite Trump's win on Tuesday, however, exit polls hinted at his potential vulnerabilities in a general election campaign. He faces four sets of criminal charges for a range of offenses, including his efforts to overturn his 2020 defeat and his retention of classified documents after leaving the White House in 2021.
Nearly half of the voters who participated in the Republican primary said he would not be fit to serve if convicted in court, according to exit polling by Edison.
A similar number of voters said they do not believe Biden legitimately won the 2020 election, echoing Trump's false claims that the result was tainted by fraud.
Edison projected Biden would win the New Hampshire Democratic primary.
There were also warning signs for Biden, however. More than two-thirds of Republican primary voters said the economy was either poor or not good, an area where Biden has struggled to highlight his administration's accomplishments.
Republicans made up a smaller share of voters in the primary relative to the state's 2016 Republican contest in the state, the exit polls showed. Some 47 per cent of voters considered themselves Republican, compared to 55 per cent in the 2016 primary. Eight percent said they considered themselves Democrats, compared to 3 per cent in 2016. The share of independents was little changed at 45 per cent.