LONDON — Britain’s House of Commons is likely to endorse on Monday a report that found Boris Johnson lied to lawmakers about lockdown-flouting parties in his office, a humiliating censure that would strip the former prime minister of his lifetime access to Parliament.

Lawmakers debated the report by the Privileges Committee that found Johnson in contempt of Parliament, and were expected to approve its findings. It was unclear whether there would be a formal vote or whether the report would be approved by acclamation.

House of Commons Leader Penny Mordaunt urged lawmakers to “do what they think is right.” Mordaunt, a Conservative like Johnson, said she would vote to endorse the report if it came to a formal vote.

“This matters because the integrity of our institutions matter. The respect and trust afforded to them matters,” she said. “This has real world consequences for the accountability of members of Parliament to each other and the members of the public they represent.”

Johnson responded with fury to the report, branding its conclusions “deranged” and accusing its members of “a protracted political assassination.”

But only a handful of his staunchest political allies said they would vote against the committee’s conclusions, and many lawmakers from the governing Conservative Party were absent from the House of Commons benches as the debate began. Prime Minister Rishi Sunak, wary of riling Johnson’s remaining supporters, declined to say whether he would participate in the debate.

“He’s got a number of commitments,” including a meeting with Sweden’s prime minister, said Max Blain, Sunak’s spokesman. “It will depend on how the timings in Parliament play out.”

Johnson, who turned 59 on Monday, also was not there. He stepped down as prime minister in September 2022, but remained a lawmaker until June 9, when he quit after receiving notice of the privileges committee’s findings.

Monday’s debate was the latest aftershock from the “partygate” scandal over gatherings in the prime minister’s Downing Street headquarters and other government buildings in 2020 and 2021.

The revelation that political staffers held birthday gatherings, garden parties and “wine time Fridays” during the pandemic sparked anger among Britons who had followed rules imposed to curb the spread of the coronavirus, unable to visit friends and family or even say goodbye to dying relatives in hospitals.

Memories were revived this week by the Sunday Mirror newspaper’s publication of video showing staffers drinking and dancing at an event at Conservative Party headquarters in December 2020, when people from different households were banned from mixing indoors.

London’s Metropolitan Police force said that it was examining footage of the event, which the BBC reported was billed as a “jingle and mingle” Christmas party.

Johnson initially denied that any parties took place at the prime minister’s office, and then repeatedly assured lawmakers that pandemic rules and guidance were followed at all times. The committee concluded that those assurances were misleading and that Johnson failed to correct the record when asked to do so.

It said Johnson “misled the House on an issue of the greatest importance to the House and to the public, and did so repeatedly.”

The panel — made up of four Conservatives and three opposition legislators — said Johnson compounded the offense with his attacks on the committee, which he called a “kangaroo court” engaged in a “witch hunt.”

It concluded that Johnson’s actions were such a flagrant violation of the rules that they warranted a 90-day suspension from Parliament, one of the longest ever imposed. A suspension of 10 days or more would have allowed his constituents to remove him from his seat in the House of Commons.

Johnson escaped that sanction by resigning — “at least for now,” he said, hinting at a potential comeback. That could prove difficult. He faces being stripped of the lifetime pass to Parliament’s buildings customarily given to former lawmakers.

While some Conservatives still laud Johnson as the charismatic populist who led the party to a landslide victory in 2019, others recall how his government became so consumed by scandals that he was forced out by his own party less than three years later.

His legacy is a headache for Sunak, a fellow Conservative who took office in October with a promise to restore professionalism and integrity to government.

The Conservatives, who have been in power since 2010, trail the main opposition Labour Party in opinion polls, with an election due by the end of 2024.

The party faces electoral tests before that in four special elections for seats vacated by Johnson, two of his allies and a fourth Tory lawmaker who quit over sex and drugs allegations.