As a member of the Conservative Party, Carswell was first elected MP for Harwich in 2005, and then for Clacton in 2010. In August 2014, he changed his political allegiance to the UK Independence Party (UKIP), and announced his resignation as an MP. He stood in the subsequent by-election and was returned under his new affiliation, becoming the first elected MP for UKIP. He stated that he was joining UKIP out of a desire to see "fundamental change in British politics" and because he believed "many of those at the top of the Conservative Party are simply not on our side. They aren't serious about the change that Britain so desperately needs."