(ShareCast News) - As the hype surrounding the US presidential election reaches fever pitch, bookmakers are seeing record numbers of flutters for a political event, according to Betfair.National opinion polls show a tight race ahead of Tuesday's final polling day, with results set to come out late into the night on Tuesday.Hillary Clinton appears to have a marginal lead over Donald Trump in the major national surveys, and bookmakers are backing the Democrat to come out on top when all is said and done.Internet betting exchange Betfair said on Sunday that its "Next President" market was set to surpass Brexit as the most traded political event, with roughly $130m being put on the line already.$159m was bet on the UK's referendum on whether to leave the European Union in June."We think it is because (of) how raw the Brexit (vote) is in people's minds - they're not convinced yet that it's a done deal," said Betfair spokesperson Naomi Totten.Irish bookmaker Paddy Power has said that the election is "definitely on course to be the biggest political event" for them, despite admitting that political betting is still a "niche market"."Trump is such a huge celebrity," said Feilim Mac An Iomaire, explaining the popularity of the US election market.UK-based Ladbrokes said that double the amount of money had been wagered on the 2016 election compared with its predecessor in 2012, when Barack Obama defeated Mitt Romney.All three bookmakers reported Clinton to have an 83% chance of winning on Tuesday, but analyst Adam Jepsen from Financial Spreads has said there is a discrepancy between the betting odds and how financial markets see the outcome.Referring to the news which emerged over the weekend of the FBI's clearing of Clinton after a further probe into her private email server, Jepsen said both bookies and markets reacted."The betting markets reacted immediately to the news and Trump is back to 5/1 to be the President, i.e. the price he was on Thursday 27 October and before the email saga reappeared," he said."For once though, the financial markets might be taking a more sensible and cautious approach. With such a tight election it makes sense that the markets don't get too getting carried away with the news."