Boris Johnson’s political future could be decided within weeks by a group of MPs investigating claims he misled parliament over Partygate, the Guardian has been told. After holding off from doing anything that could be seen to influence the local elections or overshadowing King Charles’s coronation, the privileges committee is preparing to bring its inquiry into the former prime minister to a close. Sources said that 23 and 24 May had been pencilled in to try to finalise a draft report that will rule on whether Johnson misled MPs about his knowledge of law-breaking parties in Downing Street during Covid. The seven-member committee, which has a Conservative majority, will hold private meetings to sift through the evidence in an effort to come to a conclusion about Johnson’s conduct, according to insiders. The hope is that the more than year-long inquiry can move to its last stage before the Commons goes into recess on 25 May. However, the process is far from straightforward. It could take longer if MPs are split over whether Johnson misled parliament, and the sanction he would face as a result. Once a draft report has been signed off by the privileges committee, Johnson will get two weeks to respond before the final report is published. Rishi Sunak’s government will then have to table a motion to endorse the findings. But the issue could be dragged out further if Johnson or his allies try to fight any sanction by amending the motion – as happened when former MP Owen Paterson tried to escape being punished for lobbying. Johnson has maintained his innocence. A spokesperson for the former PM said: “We continue to cooperate fully with the committee and will study its findings when they are brought forward. Mr Johnson did not knowingly, deliberately or wittingly mislead parliament.” Some observers believe a recent precedent has been set for breaking Covid laws in the form of a ruling about former SNP MP Margaret Ferrier. She is appealing against a month-long suspension from the Commons – well above the threshold of 10 days that triggers a possible byelection. While the punishment was imposed at the end of March by the standards committee, on which all the privileges committee MPs sit (bar Harriet Harman), there was a notable split. Three Tories and one SNP MP tried to reduce the sanction to nine days, and were only defeated due to being outweighed by lay members. There are no lay members on the privileges committee, so it is unclear what the result might mean for Johnson. Despite reams of evidence being collected – including WhatsApp messages, door logs and testimony by Johnson himself – being able to verify he deliberately misled MPs will be challenging. An insider with knowledge of the process said it had been “very difficult to prove what he had in his head”. There is no mechanism for MPs to appeal against findings by the privileges committee, so there may be a push for the system to be reformed if the committee finds against Johnson. A House of Commons spokesperson said the committee’s makeup reflected the “political balance” of all MPs, and that each member had been appointed by the house. They added that the decision to carry out the inquiry was made by the Commons “as a whole” on 21 April last year, and that the committee remained “duty bound to proceed with the inquiry”. Meanwhile, the Guardian has been told that taxpayer-funded legal support for Johnson will be extended for a third time. After an initial budget of £129,000 was set aside for four months, covering August to December 2022, the total rose to £220,000 and the contract with law firm Peters & Peter was extended until February 2023. As the inquiry dragged on, the contract was extended again until 30 April. While no update has been made to the government website, sources said the funding would be extended again. The use of public money to cover Johnson’s Partygate defence has come under fire from Labour, and is being scrutinised by the National Audit Office, which acts as the government spending watchdog. • This article was amended on 4 May 2023 to clarify that it is a draft report being prepared by the privileges committee; the report will only be final after Boris Johnson has had the opportunity to respond.