Rory Stewart is going to stand as an independent candidate to be Mayor of London, he has announced.
It comes just hours after he quit the Conservative Party on Friday.
The former Cabinet minister was among the 21 rebels who had the whip removed by Boris Johnson when he defied him in the Commons by backing a move designed to block a no-deal Brexit.
The Penrith and The Border MP had run against Johnson in the race to lead his party in June.
On Friday morning, he tweeted: “It’s been a great privilege to serve Penrith and The Border for the last ten years, so it is with sadness that I am announcing that I will be standing down at the next election, and that I have also resigned from the Conservative Party.”
In response, Labour leader Jeremy Corbyn tweeted: “Rory Stewart wholeheartedly backed Tory cuts that have ripped the heart out of our communities and done so much damage to our police, NHS and schools. He would be a disaster for London.”
Tory mayoral candidate Shaun Bailey said: “I welcome any candidate’s decision to stand and hold Mr Khan to account over his woeful record in London.
“We have all suffered for too long under a mayor with no plans, no ideas for London and entirely focused on moving back to Westminster to take over the leadership of the Labour party.
“London faces real challenges and that’s why I will continue to focus on serious violent crime and how we’re going to get a grip on the violence on our streets.”