Former education secretary Nicky Morgan has said she would not serve in a government led by Boris Johnson - although stressed she would not resign as a Conservative MP if he came to power.
Morgan, who chairs the Treasury Select Committee, told the BBC she was "very unlikely to be asked, but the answer [to whether she would join a Johnson-led Cabinet] is no".
However she insisted she would remain within the party, even if it were led by the former foreign secretary.
"I have been in the Conservative Party for the best part of 30 years. I am not going anywhere. I believe that there is a role for a centre-right party in our political system. I am a one nation Conservative and that is what I shall stay and fight for," Morgan said.
The senior backbencher was speaking after a weekend dominated by blue-on-blue attacks, after Johnson said Theresa May's Brexit plan would put the UK constitution in a "suicide vest".
His comments provoked a backlash from two of his former Foreign Office colleagues. Sir Alan Duncan said it was "one of the most disgusting moments in modern British politics", adding "this is the political end of Boris Johnson".
Difid minister Alistair Burt blasted it as an "outrageous, inappropriate and hurtful analogy".
Meanwhile Foreign Affairs Select Committee chair Tom Tugendhat, who has served in the military, recalled his direct experience of a suicide bomber, saying: "Some need to grow up. Comparing the PM to that isn’t funny."
Although some Conservative MPs including Nadine Dorries and Zac Goldsmith supported Johnson's comments, others have warned the would-be leader is so toxic they would quit the party to stop him taking the helm.
The Daily Mail reports that at least a dozen Tories would resign the party whip, losing the government's majority.
Sarah Wollaston, who chairs the Health Committee, was among those to go public with her threat.