General Motors and the Canadian union Unifor began the final stretch of talks on Saturday, divided ahead of a looming strike deadline over union demands that the U.S. carmaker commit to new vehicle models at its Oshawa, Ontario plant.

The union said GM was chosen as Unifor’s strike target for the talks, with any deal setting the pattern for the next round of talks with other manufacturers, including Fiat Chrysler Automobiles and Ford Motor Co.

A four-year contract covering some 20,000 Canadian autoworkers at Fiat Chrysler, Ford and GM expires on Sept. 19. If GM and Unifor do not reach a deal, workers would go on strike as of 12 a.m. EDT Tuesday.

GM’s plant in Oshawa, just east of Toronto, is on the verge of shutting one of its two assembly lines, with several vehicles either already produced elsewhere or expected to move in 2017.

Unifor has said it has made no progress in getting a new vehicle commitment for Oshawa.

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GM on Friday said only that it remains focused on working with Unifor to reach a “mutually beneficial and competitive new agreement,” but did not reiterate its previous stance that it will make future product decisions for Oshawa only after a labor agreement.

A strike at Oshawa, which assembles the Chevrolet Impala, Buick Regal and Cadillac XTS sedans as well as some other overflow work, would not cause much hardship for GM.

But if workers at its Ingersoll CAMI plant, who have the same union but a different contract, support the strike and refuse to install engines and transmissions diverted from U.S. or Mexican plants, it would be more damaging for GM. The CAMI plant assembles GM’s strong-selling Chevrolet Equinox and the GMC Terrain.

Unifor, which represents more than 20,000 autoworkers, has said its top priority is securing production of new vehicle models. Pensions and wages are also on the table.

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Nearly all of Canada’s auto industry is in the province of Ontario, which some automakers have found more expensive than other places, such as the southern United States and Mexico.

Between 2001 and 2013, some 14,300 jobs were lost in vehicle manufacturing in Canada, according to Hamilton’s Automotive Policy Research Center.

Automakers, however, had agreed to make investments during bargaining.

The U.S. United Auto Workers has said it will support its Canadian counterpart, but declined to say whether it would refuse work at American GM plants in the event of a strike north of the border.