Backbench Tory Nigel Mills said: “I don’t think the PM can survive or should survive breaking the rules he put in place … He’s been fined, I don’t think his position is tenable.”
Mr Mills, MP for Amber Valley, said the public was “rightly angry” over parties. “When they were observing the very strictest of the rules, people who were making the rules didn’t have the decency to observe them.”
He also told BBC Radio Derbyshire that “we have to have higher standards than that of people at the top” – saying he “dreads to think” how many more fines could be issued.
Mr Johnson looked set to avoid an initial fallout from becoming the first prime minister to be hit with criminal sanctions while in office over a law-breaking birthday bash held for him at No 10.
Cabinet ministers tweeted in support of Mr Johnson, praising his leadership during Covid and Brexit and also pointing to the war in Ukraine.
Culture secretary Nadine Dorries arguing that the Tory leader had “been clear about what happened on” in June 2020 and had “offered a full apology”.
Veteran Tory MP Sir Roger Gale, a vocal critic of the PM, said now was not the time to “unseat” Mr Johnson, with Russia’s attack on Ukraine to deal with.
But Sir Roger said that while he thought Johnson had “effectively misled the House of Commons” and “is clearly going to have to be held to account”.
Scottish Tory leader Douglas Ross echoed his colleagues’ sentiments, saying it “wouldn’t be right” to remove the PM “at this time” during the Russian invasion of Ukraine.