Britain’s opposition Labour Party on Wednesday published details of its attempt to instigate a parliamentary investigation into whether Prime Minister Boris Johnson misled parliament in his initial response to reports of COVID breaches in his office.

Lawmakers will on Thursday vote on a motion which, if passed, would refer Johnson to parliament’s Committee of Privileges to consider whether his conduct amounted to a contempt of the House of Commons.

Johnson on Tuesday apologised to parliament after he was fined by police for breaking lockdown rules, saying he did not know a birthday gathering at the height of the pandemic was in breach of the rules he had set.

Labour and other opposition parties are pushing for Johnson to resign and hope that a finding he held parliament in contempt might increase pressure on him. Johnson has said it is time to focus on other pressing international and domestic issues.

The motion set out several instances in which Johnson told parliament that rules had not been broken and that parties had not taken place.

Thursday’s debate, starting at 1030 GMT, will likely fail to trigger an investigation as some of the initial anger within Johnson’s Conservative Party about multiple accusations of lockdown breaches in government has died down.

To pass, the motion would require a widespread rebellion among his fellow Conservatives, as the party have a large majority in parliament.

Nevertheless, the debate will be closely watched to gauge the depth of support Johnson retains among his peers, with police still investigating several other gatherings which may have broken the pandemic rules.