Nearly 4,300 autoworkers in Canada went on strike against General Motors early Tuesday.

GM and Unifor, the union that represents autoworkers in Canada, failed to reach a tentative agreement by the time Unifor's contract with GM expired at 11:59 p.m. Monday, prompting Unifor to order a strike at midnight for 4,280 members, it said.

It is the first strike of an automaker in Canada since 1996 and comes after the union reached a tentative agreement with Ford Motor Co., which the workforce ratified on Sept. 24.

The affected facilities are GM's Oshawa Assembly Complex and CCA Stamped Products, St. Catharines Propulsion Plant and GM's Woodstock Distribution Center, all in Ontario. Unifor Local 88 members at the CAMI Assembly Plant in Ingersoll, Ontario, are covered by a separate collective agreement and continue operations. 

“This strike is about General Motors stubbornly refusing to meet the pattern agreement" the union got with Ford, said Unifor National President Lana Payne. She said the Unifor members at the GM facilities will stay on strike until a pattern agreement is met.

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In a statement, GM Canada Communications Executive Director Jennifer Wright said, “While we have made very positive progress on several key priorities over the past weeks, we are disappointed that we were not able to achieve a new collective agreement with Unifor at this time. GM Canada remains at the bargaining table and is committed to keep working with Unifor to reach an agreement that is fair and flexible."

Unifor's Payne said in a media briefing that the remaining key issues are the union's pension demands, income that supports retired workers and meaningful steps to transition temporary workers into permanent, full-time jobs.

“When you’re looking at an agreement we reached with Ford Motor Co. … it was economically significant, a lot of improvements. It was the first pension improvement in 15 years with our Ford members. We bargained the highest wage increases that we’ve seen bargained here in Canada," Payne said, noting the union achieved job security too around the transition to electric vehicles.

The Ford agreement includes a 15% increase in wages over the contract term and employees in a defined contribution retirement plan hired on or after Nov. 7, 2016, would be enrolled in a new pension plan in 2025 that would include monthly pensions for workers and surviving spouses. Other improvements include an increase in the monthly benefit for those workers in a pension plan.

Payne said Unifor made some progress with GM throughout Monday, but not enough for a tentative agreement.

"We’re negotiating and will stick with it until we get a deal our members will support," Payne said. "We’ve been very clear from the beginning that we expect GM to live up to this agreement with Ford … we’re showing GM that we mean business here and we want to get the pattern deal we got with Ford."

Unifor's U.S. counterpart, the UAW, has been on strike since Sept. 15 when it launched a targeted Stand Up Strike against GM, Ford and Stellantis, the company that makes Chrysler, Dodge, Jeep, Ram and Fiat vehicles. It's expanded the strike twice since that time to include all 38 of GM and Stellantis parts distribution centers and then to Ford's Chicago Assembly and GM's Lansing Delta Township Assembly plants on Sept 29. About 25,000 UAW autoworker members are on strike of the 150,000 in the United States.

Contact Jamie L. LaReau: [email protected]. Follow her on Twitter @jlareauan. Read more on General Motors and sign up for our autos newsletter. Become a subscriber.