OTTAWA – The former cabinet minister who is at the centre of the ongoing SNC-Lavalin affair has been invited to testify on the allegations of PMO interference, as Prime Minister Justin Trudeau faces new calls from the opposition in both the House and Senate to launch new lines of inquiry into the allegations.

This development came on Tuesday, just a day after the resignation of his closest adviser, Gerald Butts.

It was the first day that Parliament has been in session since the scandal broke, and the opposition Conservatives and New Democrats came armed with multiple lines of attack after proclaiming that many key questions remain unanswered – especially after Monday’s high-profile resignation of Butts, Trudeau's principal secretary.

Butts, a longtime friend of the prime minister, has denied the allegations that he or anyone in the Prime Minister'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 the Quebec engineering and construction giant.

The ongoing scandal continues to develop rapidly, and question period was completely dominated by questions about SNC-Lavalin, Butts' resignation, and Wilson-Raybould's involvement.

Facing the barrage of opposition questions today and calls to "let her speak," Trudeau said that his government "has always and will always stand up for the institutions and the principals that underlie the strength of our democracy," to the tune of heckles from the other side.

Wilson-Raybould surprised some by showing up on the Hill today, and taking her seat on the government’s front bench. While she did not answer any questions in the Commons, despite being referenced in many, she did speak briefly to reporters after an unanticipated meeting with her former ministerial colleagues.

Her meeting with cabinet was a request Trudeau said she made as part of an extended meeting, the first since she resigned exactly a week ago.

During her post-meeting remarks, Wilson-Raybould confirmed she remains a member of the Liberal caucus but would not say whether she was pressured by the PMO, citing ongoing consultation with her legal counsel.

To date Wilson-Raybould has cited solicitor-client privilege, given she was the former lawyer to the government, as the reason she has been unable to comment either to confirm or deny any of the allegations that have arisen before and after her resignation from cabinet last week.

Justice Minister David Lametti confirmed on Tuesday that Trudeau has asked him for legal advice about potentially waiving solicitor-client privilege in this case, as he has been repeatedly asked to do. Lametti said that his advice will be given to Trudeau “in due course.”

justin trudeau

House committee invites Wilson-Raybould

In an about-face from their stance less than a week ago, the Liberal MPs on the House Justice Committee voted in favour of calling Wilson-Raybould to testify as part of its study of the ongoing SNC-Lavalin affair and alleged PMO political interference. Though, they once again shot down the prospect of calling anyone from the PMO, or Butts, to appear.

During a closed-door meeting to discuss next steps for its probe on Tuesday afternoon the committee supported a motion from Liberal MP Iqra Khalid to invite Wilson-Raybould to appear.

The committee has also agreed to invite a few academics to participate in the study who were not already on the witness list. It has also added additional hours for meetings, so it will be meeting on Wednesday and Thursday of this week, and next Monday.

It was not immediately clear how soon Wilson-Raybould will appear, should she agree to, though it would likely be before next week, said chair and Liberal MP Anthony Housefather.

Housefather vowed to refrain from any partisan commentary while the study is going on, after he had to apologize last week for floating Wilson-Raybould was shuffled because she didn’t speak French.

Last week's meeting saw the Liberal majority vote to limit the scope and witness list of its study into the case and the broader surrounding legal principles in a way that the opposition has characterized as a "cover-up."

The opposition parties wanted to have the committee hear testimony from Wilson-Raybould and other key figures in the Prime Minister's Office. Instead the only witnesses they’d agreed to hear from initially were Lametti, his deputy minister at Justice Canada, and Clerk of the Privy Council Michael Wernick.

Conservatives on the committee tried again Tuesday to get approval for their full desired witness list that includes several others who are believed to be at the centre of this affair, including Butts, senior advisor to the Prime Minister Mathieu Bouchard, and former ministerial Chief of Staff to Wilson-Raybould, Jessica Prince. That was unsuccessful.

Deputy Conservative Leader Lisa Raitt said she is very disappointed that no one from the PMO has been asked to testify. "Especially given that Mr. Butts yesterday gave a blanket denial, surely he must be tested on his denial that he gave so freely yesterday. Why wouldn’t they want him to come to the justice committee to speak about it, especially given we're going to be doing this over such a short period of time," Raitt said.

The question for the opposition now is, whether Wilson-Raybould will actually be able to speak, or will have to continuously cite solicitor-client privilege.

"We don't know if she'll have both hands tied behind her back or simply one," said NDP vice-chair Murray Rankin.

Following Wilson-Raybould’s testimony the committee will meet to discuss next steps, said Liberal MP and committee member Randy Boissonnault, who last week said that the committee did not have the resources to conduct a full investigation and called the Tory approach a “witch hunt.”

"We want to hear from Ms. Jody Wilson-Raybould," he said Tuesday.

West Block Commons

House, Senate requests to dig deeper

In the Senate, which resumed its full sitting for the first time this year, Conservative Senator Larry Smith has presented a motion calling on the Senate Legal and Constitutional Affairs Committee to invite Trudeau, Wilson-Raybould, Lametti, Butts, the prime minister’s Chief of Staff Katie Telford, and senior adviser Mathieu Bourchard to appear as witnesses, and to submit a final report no later than June 1.

It is yet to be seen whether the Conservatives in the Senate will have support from enough of the contingent of Independent senators to have this request granted.

In the House, the NDP tabled an opposition day motion on the SNC-Lavalin affair, calling for the government to launch an independent public inquiry, similar to the commission that occurred as part of the Liberal sponsorship scandal in the early 2000s.

The motion also implores the prime minister to waive solicitor-client privilege to allow Wilson-Raybould to speak.

"That the House: (a) call on the Prime Minister to waive solicitor-client privilege for the former Attorney General with respect to allegations of interference in the prosecution of SNC-Lavalin; and (b) urge the government to launch a public inquiry, under the Inquiries Act, in order to provide Canadians with the transparency and accountability promised by the Liberals in the 2015 election campaign," the full text of the motion reads.

"For a government that is pleading their innocence, they sure are acting guilty," the NDP sponsor of the motion, MP Charlie Angus, told reporters in the West Block foyer. He said Butts' resignation cannot be overstated and that the allegations have corroded public confidence in the Canadian judicial system.

"When Canadians are expecting politicians to do better and they've got a prime minister who promised to do better, they are paying attention," Angus said.

Since the scandal erupted, Trudeau has offered a variety of comments on the situation, from blaming Wilson-Raybould being ousted from the justice post in the first place on Scott Brison, who resigned last month, to saying that "the government of Canada did its job," in this case and followed the rules.

Trudeau arrived at West Block for the cabinet meeting early on Tuesday and offered no comment on the departure of his closest adviser when asked by CTV News reporters both inside and outside the building.

Speaking to reporters in the House foyer, Conservative Leader Andrew Scheer was critical of the continuously evolving messages coming from Trudeau's office.

"This scandal continues to develop and now more than ever I think it’s clear we need a full public inquiry so we can get some light shone on this issue," he said.

He alleged in the House of Commons that Trudeau’s office may have engaged in an obstruction of justice. That allegation has not been backed up by any evidence to date, as various Liberal MPs have stated when asked about the case.

Scheer said Tuesday that his caucus will support the NDP motion, which was debated throughout the day.

The vote on the motion for a public inquiry is expected on Wednesday, and will likely have the backing of the opposition parties. It remains to be seen whether any backbench Liberals will follow suit.

Government House Leader Bardish Chagger told reporters that she is "looking at” whether the Liberal majority will support the opposition motion, and will speak to Lametti about it.

Gerald Butts

Ministers praise Gerald Butts, wife speaks

Several Liberal ministers voiced their praise and respect for Butts as they arrived on Parliament Hill for the first in-person federal cabinet meeting since the story erupted 12 days ago. Many offered comments signalling they are keen to return to focusing on the mandate they were elected to fulfill, with just over eight months until the next federal election.

"It's obviously a sad moment for me and Gerry’s many friends and people who really admire the tremendous work he's done for Canada. Having said that, you know, our work goes on," said Foreign Affairs Minister Chrystia Freeland.

Butts said the allegation is distracting from the work Trudeau and his government are doing and so it’s in the best interest of the office of the prime minister that he step aside.

The allegations were reported by The Globe and Mail 11 days ago, citing anonymous sources. CTV News has not independently verified the story. Butts was not specifically named in the initial report.

Though, the PMO had told reporters last week that Wilson-Raybould raised the SNC-Lavalin case with Butts in December, and that at that time he had told her to raise it with the clerk of the Privy Council. Trudeau has also said that Wilson-Raybould had asked him in the fall if he planned on telling her what to do in regards to the case, to which he said it was a decision only she could make.

Public Services and Procurement Minister Carla Qualtrough said she has worked closely with Butts and that he's a "good guy," who has "done a lot for our government."

"He's been remarkably effective at guiding this government towards the types of policies that make a big impact for Canadians," said Minister of Families, Children and Social Development Jean-Yves Duclos.

Finance Minister Bill Morneau said that he has “an enormous amount of respect for Gerry Butts.”

"My sense is that he's decided, I think appropriately, to defend himself against people saying things that just aren't true," Morneau said.

Asked if she still has confidence in the PMO, Environment Minister Catherine McKenna said "absolutely."

Meanwhile off the Hill, CTV News spoke with Butts' wife Jodi Butts at their home, where she said her husband’s statement stands, and that she supports his decision.

"I thought his statement summed up all his feelings quite well," she said.