So far in his still-young tenure as prime minister, Mark Carney has managed to win over five opposition MPs to sit in the governing Liberal caucus.

But on Wednesday, Carney is expected to lose his first caucus member.

Montreal MP Steven Guilbeault told Global News he will address the Liberal caucus Wednesday morning about his future. And while Guilbeault would not confirm exactly what he will say, some of his friends and close associates say they expect him to announce he will quit politics altogether and resign as the member of Parliament for Laurier–Sainte Marie.

Carney, asked about Guilbeault’s future on his way into the House of Commons Tuesday, declined to comment.

Guilbeault’s political future had been much in doubt ever since he quit Carney’s cabinet over the deal with Alberta that could see a new oil pipeline built to the West Coast.

Not only that, Guilbeault watched in frustration as, one after the other, Carney dismantled Trudeau-era climate and energy policies which Guilbeault had either designed or had helped implement as one of Trudeau’s environment ministers.

Get daily National news

Get daily Canada news delivered to your inbox so you’ll never miss the day’s top stories.

Guilbeault, a former Greenpeace campaigner before being recruited to run in the 2015 election, had been reviled by many in Western Canada for his association with those policies but he was — and remains — extremely popular in Quebec and with climate activists around the country.

“He stands by his  principles. That’s why he’s popular in Quebec,” said Bloc Quèbecois MP Alexis Brunelle-Duceppe (Lac-Saint-Jean) whose father Gilles represented Guilbeault’s downtown Montreal riding for 21 years.  “I hope he gets a bright future.”

Guilbeault’s departure could be a problem for Carney because it represents Carney’s first serious political blemish after a string of successes like those floor-crossers.

Several Liberal MPs have said privately there is concern in Carney’s caucus that if the Liberal Party under Carney no longer has room to accommodate a climate activist like Guilbeault, they could be politically vulnerable in parts of the country — such as B.C.’s Lower Mainland and in Montreal  — where being soft on climate can be a political liability.

“I think that we have a caucus that cares deeply about the environment, fighting climate change, and also about how we’re going to build our country in this moment,” said Environment Minister Julie Dabrusin, who will defend the Carney government’s new approach to climate change and energy policy.

“We have a range of opinions. We always have within our caucus. And that’s actually what makes us stronger, because people bring all their different ideas. So that’s how we work together.” 

– With a file from Mackenzie Gray

&copy 2026 Global News, a division of Corus Entertainment Inc.