More than half of voters think that Boris Johnson should resign as prime minister after he was fined by police over partygate allegations.

The prime minister attended his own birthday party in the Cabinet room in Downing Street in June 2020, when the rest of the country was under coronavirus restrictions.

On Tuesday, Mr Johnson offered a “full apology”, but when asked if he would quit, he added: “I want to be able to get on and deliver the mandate that I have, but also to tackle the problems that the country must face right now.”

A snap poll for YouGov found 57% of voters thought he should resign and 75% said he had knowingly lied, while a survey by Savanta ComRes showed 61% said he should quit.

Mr Johnson’s immediate future will be decided by his Tory colleagues, who can trigger a leadership challenge if 54 of the party’s 360 parliamentary members demand a confidence vote.

But many senior Tories have rallied around their leader, saying now is not the time for a change in leadership.

Michael Gove and Grant Shapps were among the MPs declaring their “full support” for the prime minister.

Andrew Bridgen, however, said: “This is not the end of this matter.”

Mr Johnson is reported to have attended six of the 12 gatherings being investigated and he did not rule out the possibility that he could be facing further fines.

There is also the matter of Sue Gray’s report. The senior civil servant who gathered the evidence that triggered the Met investigation, has said she will publish her report when the police have concluded their work.

Read more: Johnson may have weathered the storm for now, but the worst could be yet to come

Sky’s political editor Beth Rigby said that the war in Ukraine is the primary reason for the reluctance of many Tories to spark a leadership change.

She said: “The popular refrain – even from those who were openly hostile to Mr Johnson just a few weeks back – is ‘now is not the time’.

“The prime minister is considered by his MPs to be having a ‘good war’ and attempting to remove him in the midst of the biggest conflict in Europe in generations would be against the national interest.

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“For all Mr Johnson’s shortcomings, (Russian president Vladimir) Putin is the enemy and the party and country should remain united against this external aggressor, however frustrated they may feel with the prime minister.”

Mr Johnson’s wife Carrie and Chancellor Rishi Sunak were also issued with fines for breaking lockdown rules.

They are all understood to have paid £50 each – a reduced rate as the fixed penalty notices were settled within 14 days.

Mr Sunak apologised, saying: “I know people sacrificed a great deal during COVID, and they will find this situation upsetting. I deeply regret the frustration and anger caused and I am sorry.

“Like the prime minister, I am focused on delivering for the British people at this challenging time.”

A spokesperson for Carrie Johnson said: “While she believed that she was acting in accordance with the rules at the time, Mrs Johnson accepts the Metropolitan Police’s findings and apologises unreservedly.”