Jacob Rees-Mogg has accused Rishi Sunak of “disloyalty” towards Boris Johnson as the Tory leadership campaign descended into a bitter war of words.
The Brexit opportunities minister also ruled out ever serving in a government led by the former chancellor - and launched a furious attack on his record in the Treasury.
Sunak resigned from Johnson’s cabinet last week, helping to trigger a wave of ministerial walk-outs which ultimately led to the prime minister announcing he would stand down.
Rees-Mogg, one of the outgoing PM’s closest allies, is backing foreign secretary Liz Truss’s bid to prevent Sunak entering Number 10.
Asked on Sky News if he would take a job in a Sunak cabinet, Rees-Mogg said: “No, of course I wouldn’t.
“I believe his behaviour towards Boris Johnson, his disloyalty, means that I could not possibly support him. He wouldn’t want me in his cabinet anyway.”
Sunak has faced accusations that he plotted his leadership bid for months before resigning - claims denied by his campaign team.
Rees-Mogg added: “I couldn’t support somebody who has been so disloyal to the current leader of the party from inside cabinet.
“If you’re bound by collective responsibility, you should stick to that whilst you’re in the cabinet.”
Rees-Mogg failed to deny describing Sunak as a “socialist” during a cabinet meeting last week.
But he said: “I think as a chancellor he made decisions that were of the left rather than of the right, that he was a tax increasing chancellor.
“I didn’t support the decisions he made, I thought we should have been looking at keeping expenditure under control, rather than raising taxes.
“I think the corporation tax rise is bad for business, bad for investment in the UK. The national insurance hike hits employers just after we’re getting over the Covid problem and makes life harder for employees when we’re in the midst of a cost of living crisis. I think these were bad tax rises.”
His comments came as Tory MPs prepare to vote in the first round of the leadership contest.
Sunak is the bookies’ favourite, followed by trade minister Penny Mordaunt and then Liz Truss.