On 28 August 2014, Carswell defected from the Conservatives to UKIP. Although not required to do so, he resigned his seat as an MP, thus triggering a by-election. Less than a month before switching parties, Carswell had approved a letter from Conservative supporter Giles Watling to a local newspaper describing UKIP as a "one policy party" and saying "a vote for Ukip will be a vote for Labour". He later said he had been "decidedly cool towards the sentiments of the letter."