With just weeks to go before an election call, opposition MPs plan to put Liberals on the spot today with a motion to bring Canada's ethics commissioner before a Commons committee to testify about his conclusion that Prime Minister Justin Trudeau broke Canada's conflict of interest laws.

Conservative Leader Andrew Scheer reiterated his call for government MPs on the committee, who hold the majority, to allow Mario Dion to testify this afternoon.

Scheer told reporters Wednesday morning that he ran into Liberal MP Nathaniel Erskine-Smith on Tuesday when they attended the same event in Toronto.

"I asked him to do the right thing. I asked him to put Canada before his party and I hope he does that, I hope all members do that," said Scheer.

"We have an opportunity here for them to display that the truth is more important than their partisan interests."

A week ago, Ethics Commissioner Dion reported that Trudeau had violated the Conflict of Interest Act through his attempts to influence then-attorney general and justice minister Jody Wilson-Raybould on the SNC-Lavalin file.

'Do the right thing'

The commissioner found that, directly or through others under his direction, Trudeau sought to pressure Wilson-Raybould to grant SNC-Lavalin a deferred prosecution agreement, which would have allowed the Quebec-based engineering firm to avoid a trial on corruption and fraud charges.

"I expect the members of the committee to do the right thing and think first of honesty, transparency and ethics, rather than protecting the image of a highly unethical prime minister," said Conservative MP Peter Kent, who sits on the Commons committee on access to information, privacy and ethics.

Prime Minister Justin Trudeau and Minister of Justice and Attorney General of Canada Jody Wilson-Raybould in Ottawa in 2015. Dion found Trudeau's attempts to influence Wilson-Raybould on the SNC-Lavalin file were unethical. (Adrian Wyld/The Canadian Press)

Dion's report marked the second time a federal ethics commissioner had found Trudeau in violation of conflict of interest law. In 2017 then-commissioner Mary Dawson found the prime minister broke ethics rules when he accepted a trip to the Aga Khan's private island in the Bahamas.

Previous commissioners allowed to testify

The committee invited Dawson to testify after the release of her report, and the same invitation should be extended to Dion, NDP MP Tracey Ramsey said.

"I think it would be viewed as an obstruction for [Liberal MPs on the committee] not to have him come before the committee," said Ramsey, who will attend today's committee meeting. "This is what had happened in the past when Mr. Trudeau broke the law before, when we had the previous ethics commissioner come to the committee."

Kent also echoed the NDP's comments, saying the ethics commissioner is an officer of Parliament and reports to the committee.

"The [second] Trudeau report is much more serious and deserves much more consideration by the ethics committee," Kent said.

Commissioner ready to testify 'on short notice'

Opposition MPs say they want to see the commissioner testify as early as this afternoon. The commissioner's spokesperson, Mélanie Rushworth, said Dion "will, of course, make himself available on short notice" to appear before the committee.

Liberals hold the majority of seats on the 10-person committee. Erskine-Smith, who is vice-chair, would not comment ahead of Wednesday's meeting, his parliamentary assistant told CBC.

Green Party Leader Elizabeth May will also participate in the committee meeting Wednesday, a statement from the party said.

The opposition's track record for getting Liberals to support House of Commons committee investigations has been poor. In March, opposition MPs hurled claims of a "coverup" after Liberals stopped Wilson-Raybould from testifying a second time about the SNC-Lavalin affair.

Subsequently, the Liberals also voted against letting former Vice-Admiral Mark Norman testify after the government dropped a breach of trust charge against him related to leaks of cabinet secrets. Then in July, the Liberals shot down a bid to look into allegations the Liberals attempted to filter comments by Canada's former ambassadors to China as the diplomatic and trade relationship between Ottawa and Beijing hit new lows.