United Auto Workers (UAW) says its members have voted to reject a tentative agreement with Mack Trucks and will go on strike Monday.

73 percent of the workers voted against the last week’s proposed contract, the union said.

UAW President Shawn Fain said Sunday on X, the social media platform formerly known as Twitter, that “I’m inspired to see UAW members at Mack holding out for a better deal, and ready to walk off the job to win it.”

According to Reuters, Mack Trucks president Stephen Roy was “surprised and disappointed” that the union chose to strike.

He reportedly said in a statement, “We have demonstrated our commitment to good faith bargaining by reaching a tentative agreement endorsed by both the International UAW and the UAW Mack Truck Council.”

As three major car manufacturers are also currently on strike, news of the truck maker’s work stoppage comes as the union continues to wage strikes against them.

The Mack Truck Company is a major US manufacturer of heavy duty and medium duty trucks, with deliveries of 27,000 in 2022 and 16,000 in the first half of 2023. The company is owned by Sweden’s Volvo Group, not China’s Geely, which owns the Volvo car brand.

GM, Ford, and Stellantis, which makes Jeep, Ram, Dodge, and Chrysler cars, share many of the union’s stated bargaining goals with Mack, including increased wages, health care, and pension benefits.

For the first time in the union’s history, it has struck all three unionized automakers simultaneously.