The U.S. government raised concerns with Germany about alleged union-busting in Alabama by Mercedes-Benz Group AG, an unusual move that escalates scrutiny on the automaker’s handling of a high-stakes unionization campaign that heads to a vote next week.

Officials recently spoke about allegations by the United Auto Workers against Mercedes that include firing union activists and holding a mandatory meeting at which an executive discouraged unionization, according to a U.S. government official familiar with the discussion. The conversation included commitments that the governments will work together to promote unions and employee rights, said the person, who spoke on condition of anonymity to describe sensitive communications.

Mercedes, based in Stuttgart, Germany, denied wrongdoing, saying in an statement that the company doesn’t believe the UAW claims have merit and hasn’t interfered or retaliated against employees seeking unionization. The German embassy declined to comment. 

About 5,200 workers at Mercedes facilities in Vance and Woodstock, Alabama, are slated to vote on joining the UAW on May 13 through 17, a pivotal test of the union’s reinvigorated strength.

On a Roll

Buoyed by victories last year against Detroit’s automakers, the union is aiming to organize roughly 150,000 more workers at 14 automakers, including many where it’s suffered prior defeats. That campaign secured a landmark win last month when workers at Volkswagen AG’s 4,300-employee Tennessee auto plant voted to join the UAW, with the union getting 73% of the vote.

But Mercedes is proving a tougher target. While the company’s official principles include a section on executives remaining neutral during organizing campaigns, the UAW has alleged in complaints that the automaker repeatedly broke the law in Alabama.

The European Commission, which represents the European Union in international affairs, also raised the Alabama situation with Mercedes. The organization conveyed that “we expect them to respect both local law and European values” in advance of the Alabama election, said Olof Gill, a commission spokesperson.

Mercedes acknowledged speaking with “various authorities,” including members of the European Commission. In an emailed statement late last week, the company said Mercedes respects the right of employees to unionize and will ensure they have the chance to make an informed choice. 

Unions are more prevalent and powerful in Germany than in the U.S. Mercedes employees in Germany are covered by a union contract, have representatives on the board and elect members to a works council that has a say in its decision-making. In an emailed statement Monday, Ergun Lümali, the works council’s chairman, encouraged Alabama employees to vote for the UAW and said it was monitoring the UAW’s activities and the company’s behavior.

In February, the chief executive officer of Mercedes-Benz US International Inc., Michael Göbel, held a meeting with the plant’s workforce where he suggested that a union would mean strikes, costly dues and obstacles to conflict resolution. Mercedes informed employees last week that it was abruptly replacing Göbel, who would move effective immediately to a new role.

The anti-union push is “every day — you’re walking around thinking, ‘What’s next?’” Mercedes employee Brett Garrard said on a May 2 presentation for investors held by the SOC Investment Group, a union-affiliated shareholder advocacy organization. “Everyone’s so tired of it.”