The National Labor Relations Board has certified the United Auto Workers win in a union vote among skilled workers at the Volkswagen plant in Tennessee.
The German automaker has said it will challenge a ruling that allowed the 162 workers who repair and maintain machinery and robots at the Chattanooga factory to seek to form their own bargaining unit.
A spokeswoman for the federal panel said parties have 14 days from the election certification to request a review.
The 108-44 vote earlier this month in favor the UAW marked the union's first win in a foreign-owned plant in the South.
Volkswagen said it wants union matters decided by the entire blue-collar workforce of 1,400 employees.
