The UAW filed unfair labor charges against Honda.

The union action delays Thursday’s scheduled election at the Japanese auto maker’s U.S. plant. Officials at the National Labor Relations Board said an investigation into the charges could take 30 to 45 days, indefinitely postponing the voting by Honda’s 2,500 non-union production workers, who are to decide whether to join the United Auto Workers. Among other charges was the complaint that an employee group set up to prevent the union from organizing Honda has ties to management. Honda denied that it had anything to do with organizing the group, which claims to be a grass-roots organization.