An unnamed British former-banker has bet £3.9million on Donald Trump coming out on top in the US presidential election.

Betting insiders believe the businessman’s enormous $5million pledge is the biggest number ever wagered in politics.

The financier – who is based overseas and whose name has not been released – placed his bet with private bookmaker in Curacao in the Caribbean after speaking to ‘Trump camp insiders’.

President Trump is running against Democrat Joe Biden in tomorrow’s election – and polls are suggesting it will be a nail-biting finish.

If the anonymous businessman’s hunch is successful, however, he could walk away with almost $15million or £11.6million.

A source from the gambling industry told The Sun: ‘Word of this bet has done the rounds and we think it’s the biggest ever made on politics.’

Three in four of all bets put forward in the last week of voting has been for President Trump, bookmaker Ladbrokes revealed.

Ladbrokes’ Jessica O’Reilly said: ‘Biden looks home and hosed according to the bookies and pollsters, but even at the eleventh hour punters are continuing to back Trump at the odds on offer.’

But not everyone is so confident in that outcome. Another Briton today put £1million on bookies-favourite Biden winning and is set to take away £1.5million if he’s right.

People were still rushing to place bets on the eve of Tuesday’s election and Matthew Shaddick, Head of Politics Betting at Ladbrokes Coral Group, said it estimated about one billion pounds would be wagered globally across the industry.

US President Donald Trump’s chances of re-election gained slightly over the weekend, but Biden remained a clear favourite in online betting markets.

Betters on British exchange Smarkets give Biden a 65 per cent chance of winning, while Trump’s prospects improved to 35 per cent from 34 per cent.

UK-based internet Betfair Exchange said it also saw Trump’s odds improve on the same level.

The former vice-president has a substantial lead in national opinion polls, although the contest is slightly closer in battleground states likely to decide the race.

‘Florida is one where the polls suggest Biden is the more likely winner, but the (betting) markets have Trump as favourite,’ Mr Shaddick said.

‘The GOP have tended to overperform the polls quite regularly in that state.’

The election is on track to be by far the biggest betting event, with 271 million pounds bet so far, Betfair said. It accepts bets right up until the result is announced and sees bets with it to hit the 400 million pound mark, double that of 2016.

Most of the big-money betting occurs outside the United States as betting on politics is illegal there