General Motors’ (GM) (NYSE:GM) decision to cut a third shift at its Oshawa, Ontario, assembly plant this fall has ignited a political and labor firestorm in Canada, with hundreds of workers impacted.

Unifor, the country's largest private sector union, issued an urgent call for action this past Friday (May 2) after GM confirmed it will be transitioning the plant to a two-shift operation. The automaker attributed the decision to evolving market conditions, including the 25 percent tariff the US imposed on Canadian-made vehicles in March.

GM spokesperson Marie Binette acknowledged in an email cited by CBC that the restructuring will “impact approximately 700 workers,” though she stopped short of calling the job losses layoffs.

“We are committed to supporting employees through the transition,” she said.

Unifor sees the move as a betrayal of Canadian workers and taxpayers, who helped revive the Oshawa facility after it was shuttered in 2019. The plant, which builds light- and heavy-duty Chevrolet Silverado pickup trucks for North America, reopened in 2021 with the help of significant public investment and union-backed production deals.

“GM Oshawa was reopened thanks to the hard work of our members and significant investments by the federal and provincial governments based on a promise to maintain good jobs and production,” said Chris Waugh, Unifor’s plant chairperson in Oshawa, in Friday's release. “We will not sit idly by as that promise is eroded one shift at a time.”

Lana Payne, national president at Unifor, also weighed in, commenting, “We will not allow GM to barter Canadian jobs to gain Donald Trump’s favor. Cutting the third shift at Oshawa Assembly is a reckless decision that deals a direct blow to our members and threatens to ripple through the entire auto parts supplier network.”