Stellantis (STLA) may be moving production of the Ram 1500 pickup truck to Mexico to lower costs — at the risk of further alienating union autoworkers.

Chrysler parent Stellantis is expanding its factory complex in northern Mexico to build Ram 1500 pickup trucks, the Wall Street Journal reported on Tuesday. Stellantis has been building additional factory space next to its existing plant in Saltillo,

Such a step by the automaker would threaten its already-frayed relationship with the UAW, which has criticized moves to cut U.S. jobs.

Stellantis has been building additional factory space next to its existing plant in Saltillo, Mexico, the report said, citing people familiar with the matter.