(Reuters) - The United Auto Workers union asked the workers at Stellantis ( STLA ) to authorize a strike, accusing the French-Italian car maker of breaking its contract promises, UAW President Shawn Fain said in a letter to the union's U.S. chapters on Friday.

"We unanimously recommend to the membership that every UAW worker at Stellantis ( STLA ) prepare for a fight, and we all get ready to vote YES to authorize a strike at Stellantis ( STLA )," Fain wrote in the letter that the UAW shared in a post on Facebook.

The union's grievances center around Stellantis' ( STLA ) product and investment commitments made during contract negotiations last autumn.

"We reviewed the serious violations of our contract and patterns of illegal behavior by Stellantis ( STLA ). The evidence is clear that CEO Carlos Tavares is steering Stellantis ( STLA ) on a crash course that will cause our members tremendous harm," the letter on Friday added.

Stellantis ( STLA ) did not immediately respond to a Reuters request for comment. However, Stellantis ( STLA ) has previously denied failing to honor commitments with UAW, with its North America COO Carlos Zarlenga saying the company "has abided, and will continue to abide, by the agreement the parties reached in 2023."

Chrysler-parent Stellantis' ( STLA ) North American operations have been struggling and has attracted criticism from consumers and workers who have argued it has not done enough to invigorate demand.

The main sticking points for the UAW revolve around delays of a planned multibillion-dollar investment into a new battery plant and factory in Belvidere, Illinois and possible plans by Stellantis ( STLA ) to move production of the Dodge Durango SUV out of the United States.

Fain said earlier this month that several of its union local chapters were laying the groundwork for strikes.

Tavares has said he is focused on improving Stellantis' ( STLA ) performance in the U.S., and stated a willingness to shut down brands globally if they do not make money.