Liverpool Metro Mayor Steve Rotheram said Boris Johnson should be "in jail" rather than mounting a bid to return as Prime Minister.
In a furious attack on the ex-Tory leader, both Mr Rotheram and his Greater Manchester mayoral counterpart Andy Burnham said they were appalled at the prospect of Mr Johnson returning to the top job he quit in disgrace back in July.
Mr Burnham said: "What does it say about standards in public life, that this is even a possibility? He was asked to resign by his MPs for a reason. The idea that it's just forgotten, shows British standards in governance have eroded to nothing.
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"If they bring him back, they will be sticking two fingers up at everyone else."
Mr Rotheram said of Mr Johnson: "The man's despicable, a liar, and caused the deaths of far too many people. He should be in jail, not thinking about returning as prime minister of this country."
The prospect of Boris Johnson resuming office as Prime Minister has gathered momentum ever since the ignominious departure of his successor Liz Truss after just 44 days in Downing Street. Although Mr Johnson has not yet formally declared his candidacy, he cut short a holiday in the Caribbean to return to the UK today (Saturday) to mount an expected leadership challenge.
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