TORY rebels have hatched a timebomb plot to topple Boris Johnson if they get an elections drubbing.
They have drawn up post-dated letters to trigger a confidence vote once the results pour in.
MPs worn down by the five-month Partygate row have said a heavy defeat will be the final straw.
One admitted he has a letter to backbenchers’ leader Sir Graham Brady, dated May 6, the day after the elections.
He said: “I haven’t handed it in yet but it’s signed, sealed and ready to go.
“I’m not the only one. The elections will give us a clear idea of whether people still trust the PM.”
Jittery MPs were openly discussing a change of leadership after another week of chaos in Westminster.
Previous attempts to force a challenge were abandoned after rebels failed to gather the 54 letters required.
But pressure on the PM has intensified as they meet voters while canvassing.
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It comes as an Opinium survey showed Mr Johnson’s approval rating has hit its lowest since before Russia’s invasion of Ukraine.
Three in five people disapprove of his performance in the job and nearly as many think he should resign.
Senior MPs say the biggest backlash next month will be from “white wine” Tories not voting in the shires.
Mr Johnson also faces the possibility of further Party-gate fines — as well as the report by ethics chief Sue Gray and now an inquiry by the privileges committee into whether he misled Parliament.
One MP said: “He’s got more hurdles to clear in the weeks ahead than a horse running the Grand National — and from where I stand, he doesn’t look like a thoroughbred.”
Yesterday, Mr Johnson’s allies breathed a sigh of relief after learning he did not receive a second fine for breaking lockdown rules.
He was not among those police sent fixed penalty notices for attending the “bring your own booze” party in the No10 garden on May 20, 2020.