OTTAWA -- Opposition parties have failed to convince the Liberals to let the House of Commons ethics committee probe further into allegations of political interference in the criminal prosecution of Quebec engineering and construction firm SNC-Lavalin.

The Liberal majority on the committee voted down a motion backed by Conservatives and New Democrats that would have seen former attorney general Jody Wilson-Raybould and former Treasury Board president Jane Philpott testify about the controversy.

"The coverup continues," Conservative MP Pierre Poilievre said after the meeting ended.

Wilson-Raybould told the justice House of Commons justice committee last month that she was pressured by Prime Minister Justin Trudeau, his senior advisers and senior ad visors to the finance minister, to overrule the decision by the director of public prosecutions not to negotiate a remediation agreement with SNC-Lavalin rather than proceed to a criminal trial on fraud charges.

She believes she was shuffled out of justice in January because she wouldn't change her mind.

Trudeau has denied anything improper occurred but has been unable to change the channel from the saga that has badly hurt his public image. He said the whole thing boils down to a breakdown in trust between him, his aides and Wilson-Raybould.

During the almost two-hour-long meeting Tuesday, Conservatives and New Democrats urged their Liberal colleagues to put partisan issues aside and agree to have the ethics committee take on the probe after the Liberals ended the justice committee's investigation last week.

Liberal MP Nathaniel Ermine-Smith, who voted in favour of an NDP motion in February to hold a public inquiry on the matter, said at the ethics committee Tuesday a new probe may only result in relitigating what has already been said at the unless the two former cabinet ministers were granted wider waivers to testify on the issue.

Trudeau has not indicated any willingness to do that saying the waivers were already unprecedented and allowed for the facts relevant to the matter at hand to be made public.

The justice committee heard from 10 witnesses over five meetings but opposition parties say Wilson-Raybould named 11 people who she felt crossed the line and all of them should be asked to testify. Only two of those people were among the witnesses the justice committee did hear from.

Trudeau faced renewed questions about the controversy during a morning event in Winnipeg where he was trying to promote his government's budget introduced one week ago. He would not, however, say whether he rejected Wilson-Raybould's 2017 recommendation for chief justice of the Supreme Court of Canada.

Sources told The Canadian Press that Trudeau turned down Wilson-Raybould's recommendation that Glenn Joyal be elevated from chief justice of Manitoba's Court of Queen's Bench to chief justice of the Supreme Court over Joyal's views on the Charter of Rights and Freedoms.

Shortly after Trudeau told Wilson-Raybould he did not support her choice, the sources said Joyal withdrew his name from consideration.

In a statement Monday, Joyal said he submitted an application for consideration for the Supreme Court in 2017, only to be forced to withdraw his name for personal reasons related to his wife's health.

Instead, Trudeau appointed Sheila Martin to the high court and named Richard Wagner as chief justice. Former Conservative prime minister Stephen Harper appointed Wagner to the high court.

Trudeau said Tuesday he would not discuss the matter nor would he say whether his office was involved in the leak of what is usually a highly confidential appointments process.

Trudeau said it is the prime minister's choice of who to nominate for the Supreme Court, as well as for chief justice, and that Canadians can and should continue to have faith in their judicial system.

Speaking at the ethics committee meeting, Conservative MP Peter Kent said the breach of a highly confidential judicial appointment process would warrant a parliamentary investigation on its own. He also said the story could compromise the integrity of the appointment process, and possibly some sitting justices.