The SNC-Lavalin affair returned to the campaign trail today, with the Conservatives promising to launch a judicial inquiry into the scandal if they form government this fall.

Conservative Leader Andrew Scheer travelled to Liberal Leader Justin Trudeau's Papineau riding Thursday morning to make the announcement.

"We are here in Papineau to send a message to Justin Trudeau, and to the people in his office who are associated with this scandal, [that] we're taking this situation very seriously and we want to eliminate any possibility of it happening again," Scheer told reporters during the campaign stop.

Scheer also said a Conservative government would allow the RCMP to access information protected by cabinet confidence by applying to the Supreme Court of Canada — legislation he's dubbing the No More Cover Ups Act.

"The measures I've announced today and others I will announce later in the campaign will safeguard our democracy against the whims of sleazy and unscrupulous politicians," he said.

The issue of cabinet confidences dogged Trudeau in the early days of the campaign.

Just hours before the official dissolution of Parliament, the Globe and Mail published a story suggesting the RCMP were being stymied in their attempts to interview potential witnesses in the SNC-Lavalin case because they were shackled by cabinet confidence.

Trudeau has long argued he granted an unprecedented waiver to free up former justice minister and attorney general Jody Wilson-Raybould and others to testify in front of a parliamentary committee earlier this year, often referring to it as "the largest and most expansive waiver of cabinet confidence in Canada's history."

Responding to the Globe's story, Trudeau has said it was the Privy Council clerk who made the decision not to broaden the waiver.

"We respect the decisions made by our professional public servants. We respect the decision made by the clerk," Trudeau said at the time of dissolution.

Conservative Leader Andrew Scheer says his party would respect the independence of the judiciary. 1:12

The Liberal leader has acknowledged he needs to earn back Canadians' trust after his campaign was rocked by last week's revelations that Trudeau wore blackface on at least three separate occasions.

Trudeau, campaigning in Sudbury today, was asked what he could do between now and election day to prove he's trustworthy. He replied he would "continue to focus on the things that Canadians care most about."

"Canadians care about fighting against intolerance and racism, and I will keep standing up against intolerance every single day," he said.

NDP Leader Jagmeet Singh, who called for a public inquiry into the SNC-Lavalin affair shortly after the story broke, said his party would attack deferred prosecution agreements as the root of the issue.

"It's wrong to give corrupt companies an out," Singh told reporters at a campaign event in Campbell River, B.C.

Perceptions in Quebec

Singh also dismissed the Liberals' claim that prosecuting the Quebec-based engineering firm could lead to the loss of thousands of jobs.

"There will continue to be jobs for Canadians and Quebecers, despite the threat Mr. Trudeau referred to," he said.

Quebec's popular premier, François Legault, has said that he supports Trudeau's intentions on the SNC-Lavalin file, to save jobs, but does not always agree with his methods.

Polls have also suggested there is slightly more tolerance for Trudeau's actions on SNC-Lavalin in Quebec than there is in other parts of the country.

A Nanos poll released in September found that 44.3 per cent of Quebecers polled said Trudeau was justified or somewhat justified in his actions, which is about 10 points higher than the national average of 34.9 per cent. That same poll showed that 48.4 per cent of Quebecers said Trudeau was not justified or somewhat not justified.

An Abacus Data poll released in August found that 50 per cent of Quebecers felt Trudeau was motivated to protect jobs, while 50 per cent said his actions were inappropriate.

Ethics act violation

Last month, Ethics Commissioner Mario Dion found Trudeau violated the Conflict of Interest Act by trying to influence Wilson-Raybould to overrule a decision denying a deferred prosecution agreement to SNC-Lavalin.

In his report, Dion wrote that "the prime minister, directly and through his senior officials, used various means to exert influence over Ms. Wilson‑Raybould."

"The authority of the prime minister and his office was used to circumvent, undermine and ultimately attempt to discredit the decision of the director of public prosecutions as well as the authority of Ms. Wilson‑Raybould as the Crown's chief law officer," Dion wrote.

SNC-Lavalin is facing bribery and fraud charges related to alleged payments of close to $50 million to public officials in Libya between 2001 and 2011 to secure government contracts.

In the 2002 Babcock decision, the Supreme Court of Canada defended the principle of cabinet confidence, saying that if cabinet members' statements were subject to disclosure they might end up censoring their words, consciously or unconsciously.

"The process of democratic governance works best when cabinet members charged with government policy and decision-making are free to express themselves around the cabinet table unreservedly," it reads.