Rishi Sunak has denied he is considering resigning as chancellor after receiving a ￡50 fine for breaching Covid lockdown laws.

       The departure of his chancellor would almost certainly deliver a fatal blow to Boris Johnson’s hopes of staying on as Conservative leader, triggering a wave of letters of no confidence from backbench MPs.

       A decision to step down would starkly highlight Mr Johnson’s determination to hold on to office despite becoming the first serving prime minister to be found to have broken the law and facing charges of “failure of leadership” in the Sue Gray report into Partygate.

       The chancellor received a fixed penalty notice from the Metropolitan Police for attending a party for the PM’s 56th birthday in the 10 Downing Street cabinet room in 2020, even though he said he took part inadvertently after arriving early for a meeting.

       Reports suggested that Mr Sunak discussed stepping down after receiving the fine and had to be “talked out” of resigning by aides.

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       But asked on BBC Radio 4’s Today programme whether he considered resignation – or whether he may still be contemplating it – he replied: “No.

       “I am fully committed to helping get the country through what are some challenging months ahead and building a brighter future for the people that I’m very privileged to represent.”

       Speaking the day after unveiling a ￡15bn package of cost-of-living support, Mr Sunak said: “As you saw yesterday, I’ve got the same energy and verve that I’ve always had for this job, and I will keep at it.”