The Tories are “drifting to defeat” under Rishi Sunak, former prime minister Boris Johnson claimed.
Mr Johnson said voters in the so-called Red Wall were turning back towards Labour because the Tories were offering them “nothing to rally behind”.
In a series of interviews with his loyal supporter, former cabinet minister Nadine Dorries, Mr Johnson said: “The more time passes, the more I worry.”
He claimed the Prime Minister was a “stooge” put in place by Mr Johnson’s former aide Dominic Cummings, who has had a bitter and public falling out with the ex-premier, according to extracts published in The Times.
Mr Johnson, who quit as an MP rather than face the prospect of a by-election after being found to have lied to Parliament over the partygate scandal, said he was not bitter about his downfall.
“Never be bitter, no good can come from it,” he said.
Ms Dorries spoke to the former prime minister for her book The Plot: The Political Assassination of Boris Johnson.
Mr Johnson said: “You’ve got to have an agenda for change in the country. You know, people will feel hacked off.
“They voted for change in 2019 and they are drifting back to Labour in those Brexit seats because they’re not seeing a changed government. Nothing to rally behind, nothing. We are just drifting to defeat.”
He criticised Mr Sunak’s decision to raise corporation tax from 19p to 25p, announced while he was Mr Johnson’s chancellor.
“Why the hell are we putting up corporation tax in this way?” Mr Johnson told Ms Dorries, suggesting that it should be cut to 10p – below the level in Ireland.
“It’s absolutely mad,” Mr Johnson said.
“The whole thing needs a massive kick in the pants; I think it’s all drifting. I really, really think that unless we grip it the results of the local elections will be repeated at a general election and (Sir Keir) Starmer will be a complete disaster.”
Mr Johnson suggested his former senior adviser Mr Cummings contributed to him being forced out of No 10.
“I heard that Cummings has said he started to plot to get rid of me in January 2020,” Mr Johnson said.
“The plot was always to get Rishi in. I just couldn’t see it at the time. It’s like this Manchurian candidate, their stooge.”