This is the best summary I could come up with:

The union had set a deadline of Monday midnight for a new deal with GM after the previous contracts with the Detroit Three automakers expired on Sept. 18.

The walkout adds to the headache faced by the automaker in the U.S. where it is racking up millions of dollars in losses per week due to the United Auto Workers (UAW) strike that started Sept. 15.

GM has lost 34,176 vehicles of production since the start of the UAW strike, according to an estimate by Deutsche Bank.

The UAW has struck two GM assembly plants in the United States and 18 parts distribution centers.

GM did not immediately say Tuesday when it expects disruptions from the Canadian strike to affect U.S. auto production.

Unifor has used the "pattern bargaining" approach in its talks, reaching a deal first with Ford and then expecting GM and Stellantis (STLAM.MI) to match.

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