By Daniel J. McLaughlin
After nearly a decade as an MP, Rory Stewart - who lost the party whip last month - is standing down from the Commons and resigning from the Conservative Party.
His next step is running as an independent candidate in the London mayoral elections in 2020.
The former Tory has penned a letter to Londoners, arguing that the capital needs someone like him to sort their problems out.
However, one of his mayoral rivals says that Stewart is not a "serious contender" in the race.
In an open letter to Londoners, published in the Evening Standard, Rory Stewart outlines why people should support his campaign to be an independent mayor of the capital.
The former Tory says that his bid will break "the suffocating embrace of our dying party politics".
He also promises to make a stand against the "mutual insults... lazy habits, half-baked ideas and pointless compromises" made by political parties.
Stewart writes: "So many of our problems in London are blindingly obvious.
"You don't need me to tell you that too much of our housing is unaffordable, or that our air is grotesquely polluted, or our streets unsafe.
"Instead you need someone like me to sort these things out."
He argues that city is "suffering from a real lack of leadership, and of strong and thoughtful action".
Stewart accuses politicians of spending too much time in a political bubble, saying that local people "always know more, care more, and can do more" about local issues.
However, Stewart has been called not a "serious" candidate for the role by one of his mayoral rivals, the i reports.
Sian Berry, the co-leader of the Green Party who is running for mayor, says that he does not understand the "complex" issues in the capital.
Speaking at her party's annual conference, she said: "I do not see [Stewart] being a serious contender for Mayor.
"For too many politicians, when they are at a bit of a loose end, they will stand for London mayor. It really bothers me because the job really means getting to grips with some serious political issues - complex issues."
Berry added: "It does not strike me as something you can just dip into with this - I don't want to say superficial but it is the only way I can describe it - superficial idea that Londoners want someone they relate to who just seems like a 'nice bloke'. I do not think that will work."
She has been the Green Party's candidate for the mayoralty twice already - in 2008 and 2016 - and has been the Green London Assembly member since 2016.
Stewart is currently the MP for Penrith and The Border in Cumbria, a seat he has held since 2010. He will stand down at the next general election to focus on his mayoral campaign in London.
He lost the Tory whip in parliament - along with 20 other rebel MPs - after voting against the government to block a no-deal Brexit. Stewart announced on Friday that he had resigned from the Conservative Party.
He has held a number of roles in government, serving as the international development secretary between May and July this year. He has also been the prisons minister, the Africa minister, and the international development minister.
Stewart stood in this summer's Tory leadership campaign, passing two parliamentary ballots and finishing fifth overall.
The London mayoral election will be held on May 7, 2020.