The United Auto Workers union is petitioning the National Labor Relations Board to hold an election at a Ford Motor joint-venture battery plant in Kentucky, the union said in a release Wednesday.

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.

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