Billionaire businessman Donald Trump has won New Hampshire's Republican presidential nominating contest, while Vermont Senator Bernie Sanders won the Democratic primary over Hillary Clinton, US television networks said after early results.
With 15 percent of precincts reporting in Tuesday's race, Trump was easily winning, taking about 34 percent of the vote - compared to about 16 percent for second placed John Kasich.
Former Florida Governor Jeb Bush was running third with about 12 percent, while Iowa caucus winner Ted Cruz was fourth with about 11 percent.
Trump's win solidifies his frontrunner status in the race to be the party's White House nominee in 2016.
The reality television star's untraditional campaign has been marked by calls for the deportation of illegal immigrants and temporarily banning Muslims from entering the United States.
After a strong third-place showing in last week's Iowa caucuses, the first state to hold a nominating contest, Republican Marco Rubio needed another top-tier finish in New Hampshire to buttress his argument that he is the candidate around whom the party's leadership and wealthy donors should rally.
He appeared to have slipped after a widely-mocked debate performance over the weekend, however, and was running fifth in the early count on Tuesday with less than 10 percent of the vote.
Sanders, who describes himself as a democratic socialist, is the underdog in the national race against former Secretary of State Clinton.
He had about 57 percent of the vote in early returns, ahead of former Secretary of State Clinton, the perceived front-runner nationally, who had about 41 percent, according to the AP.
The presidential election is on November 8.