Read James Purnell's resignation statement in full, on politics.co.uk.
"I have today told the executive committee of my local party that I do not wish to be the candidate for Stalybridge and Hyde at the next general election.
I have been proud to represent the people of Stalybridge and Hyde. And this has been an extremely difficult decision to make. But I have decided that I no longer wish to be an MP.
I have spent all my working life in or about Westminster. And while this has been a huge privilege, I've realised I don't want to have spent all my life in frontline politics.
I'm looking forward to completing my project at Demos. After that my hope is to contribute ideas to public service and to the Labour party.
I do want to thank all the people who voted for me in the last two elections, and especially the members of the local Labour party, for all their support.
I hope they are as proud as I am of what we've done together, not least the improvements to our schools and our hospital that are now on the way."