Ukip are "certain" to win the forthcoming Rochester and Strood by-election after William Hill slashed the odds of a Mark Reckless victory from 1/33 to 1/100.
The bookmaker made the move after a surge of hefty wagers from political punters on the former Conservative MP.
The bookmaker said a client from Coventry staked £16,500 ($25,834, €20,650) on the Ukip candidate and another person from Cheltenham bet £12,000 on Reckless.
The updated odds mean that if someone put a £100 stake on Reckless, the punter would only win a profit of £1 if the Ukip man won.
Graham Sharpe, a media relations manager for William Hill, declared that the election is "all over, bar the voting".
"Ukip did at one time drift out to 11/10 to win this by-election and at that time the Tories were odds-on and we took bets of up to £300 for them, but recently all of the money has been for a Ukip win and their odds have now shortened to the point where they are virtually un-backable," Sharpe said.
William Hill now offers the Conservatives at 16/1 and Labour at 100/1, while the Liberal Democrats are 10/1 to retain their deposit.
The odds change comes after a poll from Lord Ashcroft revealed that Reckless was favourite to win the seat on November 20.
The Ukip candidate had a 12-point leader over Conservative rival Kelly Tolhurt (44% vs 32%).
The poll also found that Labour (17%) were the third most popular party in the constituency and the Liberal Democrats (2%) were the least popular.
Geoff Juby, the Liberal Democrat candidate at the by-election, told IBTimes UK that a Nick Clegg visit to the seat ahead of the vote was "not really needed".
"It might improve the morale of the people that are working for me. But that's about it – that's the main thing of what would be achieved," Juby said.
"Unless there is actually something for him to do when he comes down here, to me it's not really needed."