The Kentucky autoworkers, who want to join the United Auto Workers, filed for a union election Tuesday, a key development in the union’s campaign to organize Southern auto-factories and EV battery facilities.

Workers at a Ford Motor Co. joint-venture battery plant in Kentucky have formally asked the federal government to hold a vote on joining the United Auto Workers, the union said. Employees at the BlueOval SK factory publicly launched their campaign to join the UAW in November after a supermajority signed union cards.