Workers at Mercedes-Benz's plant in Vance, Alabama, outside Tuscaloosa will vote next month on whether to join the United Auto Workers labor union.

The National Labor Relations Board (NLRB) on Thursday said the 5,000 eligible workers at the factory will be able to cast their ballots from May 13-17.

The announcement comes as voting is underway at Volkswagen's only plant in the U.S., where workers are also weighing representation from the UAW as the union makes a push for expansion following its successful strike against Detroit's Big Three automakers last year.

Voting began Wednesday for the 4,100 hourly employees at Volkswagen's factory in Chattanooga, Tennessee, and will extend through Friday.

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Winning either vote would be a significant milestone for the union.

The UAW has tried and failed for years to organize nonunion U.S. auto factories, most of them built by Asian and European automakers in Southern states. But after winning record contracts with Ford, General Motors and Stellantis in the fall, the UAW is feeling a renewed momentum.

UAW President Shawn Fain vowed the union would "pull out all the stops" to organize workers at non-union automakers like Volkswagen, Tesla, Toyota, Honda, Mercedes and others after securing the wins in Detroit.

The union is promising better wages and working conditions for future members, but is facing pushback from state leaders who warn that unionization threatens jobs.

The day before voting began at VW's Chattanooga plant, the Republican governors of Alabama, Georgia, Mississippi, South Carolina, Tennessee and Texas issued a joint statement in opposition to the UAW's unionization push into the South.

"Unionization would certainly put our states’ jobs in jeopardy. In fact, in this year already, all of the UAW automakers have announced layoffs," the governors' statement said.

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"In America, we respect our workforce, and we do not need to pay a third party to tell us who can pick up a box or flip a switch. No one wants to hear this, but it’s the ugly reality," the statement continued. "We’ve seen it play out this way every single time a foreign automaker plant has been unionized; not one of those plants remains in operation."

FOX Business' Eric Revell and Reuters contributed to this report.