Liz Truss delivered a body blow to rival Rishi Sunak by saying that Boris Johnson would make a better PM than him.
Asked at a hustings event in Norwich who she we would prefer to see in No10, Ms Truss - who remained in the cabinet even as dozens of Tory MPs quit early last month - responded: "Boris Johnson."
Earlier, asked the same question, Mr Sunak had been more generous, telling an audience of Tory faithful that the party had to "move forward" and naming Ms Truss.
Mr Johnson is set to leave Downing Street in less than a fortnight after a premiership blighted by scandal after scandal.
Despite all the partying that took place during lockdown under his watch, the Chris Pincher scandal, the refurbishment of his flat using donor cash, the Owen Paterson lobbying debacle, and the illegal prorogation of Parliament - among other incidents - he remains popular with Tory members.
Last month more than 14,000 signed a petition calling for his name to be included on the ballot for the next leader as his allies rallied behind him.
Mr Sunak has been repeatedly harangued by angry Tories while on the campaign trail, repeatedly facing accusations that he betrayed the gaffe-prone PM.
Addressing this tonight at a hustings hosted by TalkTV, he said: "Oh gosh, I mean, Liz Truss, we're here in her home town.
"And regardless of that, or home area, look, we've got to move forward as a party.
"Lots of you here, I'm sure (are) upset with me for resigning, wish Boris was here, that is not going to help us move forward."
In recent weeks he has claimed to have disagreed with the Prime Minister about economic strategies and said he quit due to ethical concerns.
Foreign Secretary Ms Truss has frequently professed her loyalty to the shamed PM, who remains in office on a caretaker basis but has spent much of the last three weeks on holiday.
She looks increasingly likely to succeed him in less than two weeks, with the winner set to be announced on September 5.
One early issue Ms Truss will have to face will be her relationship with French president Emmanuel Macron.
Tonight she was asked whether he is a friend or foe, to which she replied: "The jury's out."
She added: "If I become Prime Minister, I will judge him on deeds not words."
