The United Auto Workers was petitioning for a unionisation vote at Volkswagen’s Chattanooga, Tennessee plant, Bloomberg reported.

A “supermajority” of the 4,000 eligible staff at the factory have signed union cards over the past few months, the UAW told Bloomberg. The union filed a petition on Monday asking the US National Labor Relations Board (NLRB) to conduct an election.

Bloomberg noted winning a vote at VW would be one of the union’s biggest victories in decades, and would result in the company being legally required to recognise and bargain collectively with the UAW.

After a six week strike that secured record contract victories at Detroit’s big three unionised automakers, the UAW has been attempting to organise around 150,000 workers at non union sites run by 13 manufacturers, including VW, Tesla and Nissan.

The Chattanooga factory was the first one where the union was petitioning for an election, a step the UAW had previously said it would take once it reached 70% support at a plant.

Bloomberg said the VW plant was a key target for the UAW which was narrowly defeated in unionisation votes there in 2014 and 2019.

VW said it “will fully support” the NLRB holding an election at its plant, so that each employee could vote privately on whether to unionise.

Bloomberg noted the NLRB has been investigating complaints filed by the union alleging that VW management restricted union discussions and prohibited displaying pro union paraphernalia at the Chattanooga plant.

Volkswagen has denied violating its workers’ rights and said in February it was “committed to providing accurate information that helps inform them of their rights and choices.”

In recent months, Bloomberg said, the UAW also announced reaching 50% support at a Mercedes-Benz plant in Alabama, and passing 30% signed up at a Hyundai site in Alabama and a Toyota factory in Missouri.

The UAW was still working toward its 70% target at each location, the report added.