LONDON: Prime Minister Boris Johnson faced stinging criticism on Thursday from his own Conservative MPs and the embarrassing prospect of a probe into whether he lied to parliament over the “Partygate” scandal.

Lawmakers agreed to launch an investigation by a parliamentary committee into his past denials to the House of Commons of lockdown lawbreaking in Downing Street that caused widespread public anger.

Under the code for ministers, misleading parliament is ordinarily a resigning matter but a bullish Johnson — on a two-day trip to India — insisted he was not going anywhere.

The investigation by parliament’s privileges committee will begin once London police have finished their own probe and an internal report on the scandal is published in full.

During a debate before the vote, several members of Johnson’s Conservative party broke ranks to lambast his behaviour, and indicated he no longer had their support.

The signs of a growing rebellion came after Johnson last week became the first British leader to be fined for breaking the law, as police confirmed they had issued dozens of penalty notices to his staff.

That prompted one junior minister to resign, while senior Tory backbencher Mark Harper told parliament earlier this week that Johnson was “no longer... worthy” of being prime minister.

On Thursday, Tory MP Steve Baker appeared to join him, saying Johnson “now should be long gone” and said he would support the probe.

“Really, the prime minister should just know the gig’s up,” he added.

Another Tory, William Wragg, also said he backed an investigation, noting the Commons “can be a pantomime, a farce, turgidly boring” but that “it should always be reasonably honest”.

Tory Anthony Mangnall said he could not forgive Johnson for “misleading the House”.

In India, Johnson insisted he would not quit and intended to fight the next general election — still likely at least two years away.

“I understand people’s feelings,” he told Sky News.

But he said of stepping aside: “I don’t think that is the right thing to do. What I am determined to do is make sure we continue with our agenda.”

Johnson repeatedly denied in parliament that he or his staff had breached his own lockdown laws, even as his government urged the public not to mix, leaving families unable to visit loved ones stricken with the virus or even attend their funerals.

But the fines issued in recent weeks have severely undermined his past claims.

Johnson’s single fine is related to an office gathering for his birthday in June 2020, when Britain was under lockdown.

Further penalties for other events could follow but police said Thursday they will not announce any new fines issued until after local elections on May 5.

Johnson has apologised over the scandal but remains adamant he never knowingly misled parliament, and has vowed to press on with issues including the war in Ukraine.

Thursday’s call for a cross-party probe into whether Johnson’s previous “Partygate” denials amounted to “contempt of the House” came from the main opposition Labour party and was billed as a test of Conservative loyalty to him.

In an abrupt U-turn minutes before the debate began, his government abandoned a bid to force Tory MPs to delay a decision on the matter.

The drastic reversal raised serious questions about the degree of support for Johnson among his 359 Conservative lawmakers after being dogged by “Partygate” revelations for months.

The committee has the power to sanction lawmakers found guilty of offences, including suspending them from parliament.

Labour leader Keir Starmer said support for an investigation would uphold parliament’s principle of “honesty, integrity and telling the truth”.

“It is a principle under attack, because the prime minister has been accused of repeatedly, deliberately and routinely misleading this House over parties held in Downing Street during lockdown,” he added.

Tory lawmakers appeared spooked at warnings opposition parties would name and shame them ahead of the local elections if they blocked the probe.

An election drubbing for the Conservatives could significantly add to Johnson’s woes, if more Tory MPs join the growing chorus of public critics.

One national survey this week found around two-thirds of the public spoke negatively about Johnson, compared to just 16 percent positively, with the word “liar” the most commonly shared response.