Three quarters of Republicans in New Hampshire back Donald Trump over Nikki Haley, a poll has found.

The NBC News, the Boston Globe and Suffolk University poll of registered Republicans in the state suggests that just 22 per cent support Ms Haley.

But her support swelled to 38 per cent and Mr Trump’s fell to 60 per cent when independents – who can vote in the primary – are included.

Mr Trump said at a rally last week that Democrat infiltrators were conspiring with anti-Trump Republicans to secure Ms Haley’s victory in New Hampshire.

The former South Carolina governor has vowed to not drop out if she loses Tuesday’s primary.

Defeat would all but sink her campaign for the Republican nomination.

The poll of 500 people likely to vote in the primary was conducted on Sunday and Monday.

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