The United Automobile Workers union asked a federal labor regulator to conduct an election at a factory Ford jointly owns with a South Korean battery company.

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.

A supermajority of workers at an electric vehicle battery campus in Hardin County has filed a petition with the National Labor Relations Board, asking for a union election. Employees of BlueOval SK have formally requested to vote on joining the United Auto Workers.

Shortly after announcing a union campaign at the BlueOval SK Battery Park in Glendale, workers have filed for an election to join the UAW.

The UAW is trying to rush BlueOval SK into unionization before our full workforce has the opportunity to make a truly free and informed choice,” a company spokesperson said.

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.