Happy Birthday prime minister. The Clacton by-election will be held on 9 October the Conservative Party has announced, the same day David Cameron turns 48-years-old.
Douglas Carswell triggered the by-election when he defected from the Tories to Ukip last week and the eurosceptic is on course to become Ukip's first ever elected MP.
A Survation study for the Mail on Sunday put Ukip on 64% in the constituency, with the Tories a distant second on 20%.
Carswell had been Conservative MP for Clacton since 2010, having previously served as MP for Harwich from 2005-10 before boundary changes.
Cameron has dismissed Carswell's decision to defect as "bizarre" because he had promised a referendum on the UK's membership of the EU by the end of 2017.
However victory for Ukip in Clacton, just seven months away from the general election, will be a blow to the prime minister's hopes of preventing eurosceptic voters haemorrhaging to Nigel Farage's party.
The Ukip leader has suggested that should Carswell win, more Tory MPs could decide to defect. However eurosceptic MPs have lined up to rubbish the claim.
Wyre Forest MP Mark Garnier, whose mother was a founding member of Ukip, admitted at the time of Carswell's defection that the move was a "very big deal" but dismissed the suggestion that other Tory MPs would would follow his lead as "massively hyped up".
He told The Huffington Post: "He doesn't have the following of many backbenchers. He always been outlier, always been someone who comes along with sightly selectively argued points don't necessarily make a huge amount sense under strict scrutiny," he said.