OTTAWA – NDP Leader Jagmeet Singh is calling on the federal government to launch a public inquiry into the allegations of PMO interference in the SNC-Lavalin case.

"It's become clear now that we need a public inquiry to get to the bottom of what's happened," Singh told reporters in Burnaby on Monday.

The NDP plan on tabling a motion in the House of Commons on Tuesday proposing an independent inquiry led by a former judge. It is expected MPs will vote on the proposal on Wednesday after debating it, though even if Liberal MPs side with the opposition in supporting the motion it does not compel the government to act.

The Globe and Mail has reported that Prime Minister Justin Trudeau’s Office pressured Jody Wilson-Raybould -- who was the attorney general at the time -- to have federal prosecutors pursue a remediation agreement rather than criminal prosecution in the corruption and fraud case against SNC-Lavalin. CTV News has not independently verified the story.

Wilson-Raybould has said that, as the former AG, she is "bound by solicitor-client privilege in this matter," and has not confirmed or denied reports she was pressured.

Trudeau has denied the Globe report and said that Wilson-Raybould had an obligation to raise any concerns about feeling pressure with him, and she did not. He also suggested that had Scott Brison not stepped down as Treasury Board president, Wilson-Raybould would not have been shuffled into veterans’ affairs, a move that some saw as a demotion linked to her refusal to abandon the prosecution of the case against SNC-Lavalin.

Singh said that a public inquiry is needed after what he called obstruction by Liberal MPs at the House Justice Committee last week.

At that meeting, the House committee agreed to a study on the scandal but the Liberals used their majority standing to shut down opposition calls for Wilson-Raybould and other key figures in the Prime Minister’s Office to testify. Instead the only witnesses they’ve agreed to hear from are current Justice Minister David Lametti, his deputy minister at Justice Canada, and Clerk of the Privy Council Michael Wernick.

The committee will be meeting in-camera on Tuesday afternoon to discuss other possible witnesses, the timeline for the meetings, and the potential impact on ongoing court proceedings of this probe. The study will focus on the topics at the heart of the affair: remediation agreements, the Shawcross doctrine—which has to do with the independence of the attorney general in making decisions—and the discussions between the AG and government colleagues on SNC-Lavalin.

Singh also criticized Trudeau for “repeatedly” changing his story, and restated his call for him to allow Wilson-Raybould to speak by waiving solicitor-client privilege on this matter.