While both federal cabinet ministers from New Brunswick say they have "full confidence" in Prime Minister Justin Trudeau, two Liberal MPs in the province are expressing some reservations in the wake of the SNC-Lavalin controversy.

New Brunswick Southwest MP Karen Ludwig said Wednesday she wants to see the ethics commissioner's report before making up her mind about how Trudeau handled things — especially because she's not in cabinet and wasn't privy to those discussions.

Ludwig said she stands by the work of the Liberal government but is still absorbing information about how it dealt with SNC-Lavalin.

"I think it's really important to listen to the witnesses that are still coming before the justice committee but also the work of the ethics commissioner," she said in an interview with CBC's Harry Forestell.

New Brunswick Southwest MP Karen Ludwig says she'll continue to focus on local, riding-based issues while the ethics commissioner investigates the SNC-Lavalin affair. (CBC)

"I think that's a significant position that hardly anyone is actually talking about. The ethics commissioner is a non-partisan role ... Let's hear what the ethics commissioner has to say."

Saint-John Rothesay MP Wayne Long has twice called for an independent investigation, most recently after former Jane Philpott's resignation as chair of the Treasury Board.

2 resignations

Philpott's resignation came after former justice minister and attorney general Jody Wilson-Raybould accused the Prime Minister's Office of political interference related to a criminal corruption investigation against Quebec-based engineering giant SNC-Lavalin. Wilson-Raybould also resigned from cabinet.

Wilson-Raybould has testified to the House of Commons justice committee that 11 people working for the prime minister met with her over the course of several months, "hounding" her in an effort to get a deferred prosecution agreement for the company. She said on multiple occasions, Quebec jobs and the election were brought up.

Saint-John Rothesay MP Wayne Long has twice called for an independent investigation into the SNC-Lavalin affair. (CBC)

Philpott resigned Monday, saying she had lost confidence in the Trudeau government. She and Wilson-Raybould are still in the Liberal caucus.

Prior to Wilson-Raybould's testimony, Trudeau's former top adviser Gerald Butts resigned.

He testified before the justice committee Wednesday, challenging Wilson-Raybould's version of events. The committee also heard from clerk of the privy council Michael Wernick, who denied making "veiled threats," as well as deputy justice minister Nathalie Drouin.

An ethics investigation

Nicole O'Byrne, associate professor of law at the University of New Brunswick, said an ethics commissioner's report will likely not touch the most contentious parts of the SNC-Lavalin affair — specifically the possible allegations of obstruction of justice.

"To be blunt, we're well past the scope of what the ethics commissioner can inquire into," O'Byrne said.

A public inquiry

O'Byrne said Butts's testimony wasn't provided under oath, so the committee can't uncover the truth to the extent a public inquiry can.

"[A public inquiry] can have quite a large scope and you can have the kind of evidence you need to get at the truth here," she said.

Long broke ranks earlier and voted with the opposition for a motion to launched a public inquiry into the allegations. The motion was defeated.

Federal Intergovernmental Affairs Minister Dominic LeBlanc says he has full confidence in Prime Minister Justin Trudeau. (Matt Smith/The Canadian Press)

Before Wilson-Raybould's testimony, Long told reporters he'd met with the party whip.

"The government's never happy when MPs stand different from the flow of government, but I'm always going to stand up and do what I think is right," he said.

He said he's a "party guy."

"But I'm also going to be an MP that stands up when I think I need to."

Cabinet confidence

Both New Brunswick ministers are standing by Trudeau. Dominic LeBlanc, the minister of intergovernmental and northern affairs, said he has "full confidence in the prime minister."

Health Minister Ginette Petitpas Taylor tweeted "I have full confidence in Justin Trudeau and our government."

Health Minister Ginette Petitpas Taylor says she stands by the Prime Minister. (CBC News)

LeBlanc, the MP for Beausejour, and Petitpas Taylor, the MP for Moncton-Riverview-Dieppe, joined the 31 other cabinet ministers in assuring the public that they stand behind Trudeau.

Backbencher influence

J.P. Lewis, associate professor of political science at the University of New Brunswick Saint John, said it could be difficult to say how findings from an ethics commissioner's report would affect the politics

He said cabinet members are the government, so it's important for them to align on supporting Trudeau.

Backbenchers have more freedom, he said, but also possibly less influence.

"If backbenchers en masse are getting upset with a leader with a position that the government is taking or the party is taking it's easy for there to be pressure," he said, pointing to when Tom Mulcair was pushed out of the NDP.

"We don't have any evidence that it's anywhere close to this going on with this current government," he said. "Theoretically, I mean that can happen from within but it doesn't appear that we're close to that."