A new poll has given Donald Trump a three-point lead over his rival Hillary Clinton.

According to Rasmussen's "White House Watch", which is at odds with most other polls across the US, Mr Trump has 43 per cent support among likely voters while Ms Clinton has 40 per cent support.

As for the independent candidates, the Libertarian Party's Gary Johnson has 6 per cent backing while the Green Party’s Jill Stein has just 3 per cent.

Only 6 per cent of voters are undecided, the poll found.

Rasmussen said it was too early to measure the impact of the third presidential debate which took place in Las Vegas on Wednesday night, where the two candidates discussed the economy, security, WikiLeaks and Mr Trump’s treatment of women.

The same company found the previous day that the candidates had 42 per cent support each.

Results over the last two days represent a dramatic narrowing of the gap compared to a week earlier, when Ms Clinton had a seven-point lead following Mr Trump’s graphic remarks in a leaked 2005 video where he was seen to be bragging about sexual assault.

At the third debate, Mr Trump insisted he had done "nothing wrong" and said he did not even apologise to his wife, Melania Trump, despite her ealier insistence that he had apologised.

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Rasmussen updates its results based on a three-day rolling average of 1,500 likely US voters, and the latest result was completed before the third debate between 17 and 19 October.

Mr Trump jumped on the latest poll, tweeting: "Thank you America!"

The margin of error is around 2.5 per cent with a 95 per cent level of confidence.

The poll appears to be an outlier.