The Tory deputy chairman has quit to throw his weight behind one of the candidates vying to succeed Rishi Sunak as party leader.
Matt Vickers said Robert Jenrick was the “stand out” candidate of the six competing to take on the top job.
Vickers was appointed Conservative deputy chairman by then prime minister Boris Johnson two years ago.
He announced he is quitting after chairing a northern hustings event featuring five of the six leadership candidates. Frontrunner Kemi Badenoch was the only one not to turn up.
Vickers, who backed Sunak in the last two Tory leadership elections, said: “All the candidates were good, but Robert Jenrick was the stand out.
“This process really matters - we have a mountain to climb and need a leader that can bring us back in one term. Having heard him up close, I firmly believe that that’s Robert.
“He had the clearest diagnosis of why we lost, and set out the most compelling vision for how we change, rebuild and win again. Of course, he is a strong communicator, but he crucially has the credibility we need to earn back the public’s trust.”
The six candidates will be whittled down by MPs to four in time for the Conservative Party conference in Birmingham next month, before the final two are put to the Tory membership.
The party’s new leader will be announced on November 2.
A poll released last week by Ipsos UK revealed that most Brits do not care who wins.