Auto workers launched strikes Tuesday at three General Motors facilities in Canada.

The auto worker’s union, Unifor, represents around 4,300 workers at the plants, and had warned they would walk off the job if they failed to reach agreement with GM by midnight Monday.

The action followed Unifor workers ratifying a new three-year labor contract with Ford. The union is seeking a similar agreement with GM.

Unifor national president Lana Payne says talks were continuing, and that a lot of ground needed to be covered to reach a tentative agreement.

Payne had said the union had a lot of bargaining leverage with GM because the factory in Oshawa, Ontario, is working around the clock to build profitable Chevrolet pickups.