Tory MPs are considering the aftermath of dire local election results as their next chance to oust Boris Johnson, with the prime minister preparing to apologise for his Partygate penalty. However, Downing Street is feeling bullish that Johnson has “crossed the Rubicon” after receiving his first fixed-penalty notice earlier this month, and will cling on in the face of further charges. Johnson will face a challenging day on Tuesday, forced to deny misleading the Commons over his knowledge of illegal gatherings in No 10 by clarifying his previous insistence that no Covid rules were broken. Even his most stout defenders are feeling as if their loyalty has been unreciprocated, with one saying they have been greeted with a “slap in the face”. “All I’ve got to show for it is a Boris-shaped slap mark on my cheek,” they added. In his first statement to parliament since being handed the penalty, the prime minister is expected to urge Conservative MPs to focus on “the huge priorities we need to deliver for people”, before privately addressing the entire parliamentary Tory party later that evening. Before his statement, Johnson will attend a call chaired by the US president, Joe Biden, with the leaders of France, Germany, Japan, the EU and Nato, in which they will discuss bolstering defensive weapon supplies to Ukraine and options for further sanctions against Russia. Opposition parties are pushing for the Speaker, Lindsay Hoyle, to grant MPs a vote on whether Johnson should be found in contempt of parliament, or face an investigation by the privileges committee. They believe the fines imposed by police for multiple events during lockdown in Downing Street show the prime minister misled the Commons when he said in December that “all guidance was followed completely in No 10”. While few Tories have publicly criticised Johnson since he and the chancellor, Rishi Sunak, were fined by police, some voiced concern that the prime minister would not be contrite enough in his statement on Tuesday. “I’d fine him again, because he hasn’t learned his lesson,” one raged. Another accused him of “arrogance”. It has been suggested Johnson would cite an exemption from the strict Covid rules, saying he was in his place of work and “going to events in a work capacity”. Most of those vying to oust the prime minister have turned their sights to next month, when they believe more fines may have been issued and a poor set of local election results would show the damaging effect Partygate is having on the Conservatives’ popularity. “Nothing will happen until after the May elections, which could be terrible,” a senior MP said. Another added: “I don’t think this week will be a problem. But I suspect the bigger challenges are still to come. The PM being fined multiple times will be very bad, but by far the biggest issue is the sense that the government is now tiring and disjointed. That’s what is making me nervous.” A third predicted: “The spell over colleagues might be broken when their councillors start losing in May and when the Wakefield byelection goes badly.” Some of those who went public with their calls for Johnson to quit in January have warned colleagues against following suit, saying privately that their mental health has been badly affected given the pushback and isolation they faced. Those considering submitting a letter of no confidence therefore said they wanted to wait for the right moment. “I’m not going to take the shot unless I’m confident I can take him down,” one said. Another confessed: “This unhappy Easter bunny’s keeping his powder dry.” A third sceptical MP said Johnson would “try the business as usual stance”, but cautioned: “There is public confidence but private concern about his future being expressed by lots of people.” The elections expert and Conservative peer Robert Hayward said a poor performance at the polls next month coinciding with further penalties “could trigger the whole process from January again”. But he added that if the party exceeded expectations and the war in Ukraine continued to dominate, then “there is every prospect that the results will not be clear and may not trigger anything”. Johnson’s allies were confident he would survive the fallout from receiving his first penalty notice relatively unscathed. One minister accused the Metropolitan police of “grossly overreacting” for issuing penalties to those who attended a gathering in Downing Street during the first lockdown where Johnson was wished happy birthday. They said: “Midterm local elections at a 25-30% turnout are normally 0% useful at predicting the next general election result – but will no doubt be used as a tool for bedwetting by the usual suspects.” Another supportive MP said the first fine was over a relatively minor gathering. They said it “will help dilute the grief if more serious breaches are uncovered” – meaning “people will just shrug”. A Downing Street insider also expressed confidence Johnson had “crossed the Rubicon” and said if he survived being fined once, he would probably cling on even if the police found further Covid law breaches were committed. Sunak also receiving a penalty charge and coming under fire over his previously undisclosed holding of a US green card have been viewed by Johnson’s supporters as helpful at neutralising one of his most dangerous rivals. The war in Ukraine could continue to dominate in the aftermath of the 5 May local elections. Officers from Scotland Yard are still considering evidence about other alleged law-breaking parties. Government sources told the Guardian last week there were three further events that Johnson attended for which he could be: the May 2020 “bring your own booze” summer party; a November gathering in Johnson’s flat with his wife on the day of Dominic Cummings’ departure; and a leaving do for the senior aide Lee Cain in No 10 the following day.