Donald Trump has seen a late surge of support in spread betting markets, with punters backing the controversial Republican to beat the odds and turn in a better than expected showing in the electoral college that picks the US president.

Sporting Index said that after a wave of support for Democrat Hilary Clinton yesterday, Trump has been back on the march with its punters. Its forecast for the electoral college has slumped from a Clinton high water mark of 330 yesterday to 311, with the spread at the time of writing at 305-315.

Each candidate needs 270 votes to win, with most states allocating their delegates to candidates on a winner takes all basis. Trump needs to sweep battleground states Ohio, North Carolina, Florida, Iowa and New Hampshire to stand any chance of reaching that number. He also needs to spring a surpise in Nevada or in one of the states that polling suggests are more or less comfortably in Clinton's camp.

Despite Trump's latest betting surge, Sporting Index's forecast would still see Clinton installed in the White House, with room to spare. However, with the “Brexit effect” weighing heavily on punters minds, it still promises to be a nervous night for the financial markets, which are desperate for a Clinton victory to steady nerves in the wake of the Brexit shock.

Ed Fulton, political trading spokesman for Sporting Index, said: “Punters backing Trump had been quiet over the past few days but this morning we’ve seen a surge of support for the Donald.

“The polls may have been moving against Trump in the final few days, but we’ve seen a number of elections across the world defy conventional wisdom in the past 18 months.“

Chris Beauchamp, chief market analys at IG, a financial spread betting firm, said investors and traders were “hunkering down for a long night”.

“Trading today has been conducted with a nervous eye on the US election, and while anecdotal evidence has peppered the day, investors will just have to be patient for a few more hours,” he said.

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Ladbrokes reported that the vast majority of bets continued to be for Trump although its odds on the Republican had drifted to 7-2 from 3-1 at the time of writing. The big money from high rolling punters has all gone for Clinton including one £40,000 plus bet.

Trump's odds range from 3-1 to 4-1 while Clinton can be backed at between 1-4 and 1-5. The most recent prediction by FiveThirtyEight, the US forecasting site, is that Clinton has a 71.8 per cent chance of winning based on polling and other data. That's an improvement on yesterday.