Sadiq Khan has offered to help Hillary Clinton defeat Donald Trump – pledging his successful campaign as a “template” to hers.

Mr Khan, the new Mayor of London, said he had successfully beaten the Conservatives’ “Donald Trump approach” to elections in last weeks’ vote.

“I think what we’ve shown — and I hope it’s a lesson that Hillary and others in American take on board, hope does ‘trump’ fear, forgive the pun,” he told reporters at the capital’s City Hall, according to the Politico website.

He said he was planning to travel to the US before the end of the year due to the threat of Mr Trump’s proposed policy of banning all Muslims from traveling to the US.

Mr Khan’s election has attracted interest from around the world on account of his election as the first Muslim mayor of a major western capital city.

Mr Trump, the presumptive nominee for the Republican presidential candidacy, commented on Mr Khan’s election by saying he would make an exception for him to visit the US.

But Mr Khan rejected the offer. “The idea of making an exception for me because I’m the Mayor of London demonstrates how little they understand,” he said.

Hillary Clinton is all but certain to claim the Democratic Party’s presidential nomination

Like failed Conservative mayoral candidate Zac Goldsmith, Mr Trump has been accused of running a “racist” campaign by singling out people for travel bans on account of their faith.

Mr Goldsmith was accused of using “dog whistle” tactics to repeatedly draw attention to Mr Khan’s Muslim faith – as well as attempts to link him with Islamic extremists.

Donald Trump is the presumptive Republican nominee (Reuters)

The US presidential election takes place this November, with the primary season all but over and the nominating conventions drawing closer.

The latest head-to-head polls show a fairly close race, with Ms Clinton holding a slight lead before the start of campaigning-proper.

Sadiq Khan's 5 most significant policies Show all 5 1 /5 Sadiq Khan's 5 most significant policies Sadiq Khan's 5 most significant policies Tackle the housing crisis Khan’s key policy is an ambitious target to make 50 per cent of all new homes being genuinely affordable, and improving conditions for people renting Getty Images Sadiq Khan's 5 most significant policies Freeze transport fares Khan says he will freeze London transport fares for four years and introduce a one-hour bus ‘Hopper’ ticket, paid for by making TfL more efficient and exploring new revenue-raising opportunities. He claims Londoners won’t pay a penny more for their travel in 2020 than they do today Getty Images Sadiq Khan's 5 most significant policies Make London safer Resore neighbourhood policing, tackle gangs and knife crime, and a new plan to tackle the spread of extremism, and a review of the resourcing of our fire service Getty Images Sadiq Khan's 5 most significant policies Restore London's air quality Pedestrianise Oxford Street and prioritise measures to improve London’s air quality Getty Images Sadiq Khan's 5 most significant policies Make cycling and walking safer More segregated cycle routes with a promise to spend money improving dangerous junctions Getty Images

Both candidates have unusually strong negative ratings with the general public, however.