NASHVILLE (AP) — A U.S. Supreme Court action this week in a labor case involving Macy's department store workers should persuade Volkswagen to drop its legal challenges to the United Auto Workers' representation of skilled-trades workers at German automaker's lone U.S. plant in Tennessee, union officials said Thursday.

Volkswagen is appealing National Labor Relations Board decisions that paved the way for a vote among about 160 skilled-trades workers at the plant to be represented by the UAW. The union won that election on a 108-44 , the UAW's first victory at a foreign-owned auto plant in the South.

But the company has refused to bargain with the UAW while it argues in the U.S. Court of Appeals for the District of Columbia Circuit that union representation decisions should only be made by the entire hourly workforce. Macy's made much the same arguments in its unsuccessful appeal involving a similar labor arrangement for fragrance and cosmetics sales staffers at a Macy's department store. The U.S. Supreme Court declined to take up the case.

"The Supreme Court's decision to not wade into this issue reinforces that these bargaining units are appropriate," UAW Secretary-Treasurer Gary Casteel said in a statement. "We renew our call for Volkswagen to drop its frivolous appeal and meet employees at the bargaining table in Chattanooga."

Volkswagen declined to comment.

The labor relations board has drawn the ire of Republicans and national business groups such as the U.S. Chamber of Commerce for allowing the proliferation of what they deride as "micro" bargaining units.

Tennessee Sen. Bob Corker, a former Chattanooga mayor and a vocal UAW opponent, last month co-sponsored legislation seeking to reverse the NLRB's precedent-setting 2011 decision in favor of certified nursing staff creating a 53-person bargaining unit at Specialty Healthcare and Rehabilitation Center of Mobile, Alabama, at the exclusion of other workers there.

The Specialty Healthcare case became the basis for dozens of smaller groups gaining union representation, including the skilled-trades workers at Volkswagen, FedEx drivers and production workers at a Nestle ice cream plant in Maryland.

Corker called his bill an "effort to reverse a disruptive action that fragments the workplace."

The Macy's case involved perfume and makeup salespeople at a store in Saugus, Massachusetts. The company argued that the entire 120-person sales staff at the store should have been eligible to decide on collective bargaining rights through the United Food and Commercial Workers Union, rather than just the 41 people working in the cosmetics and fragrances department.

But the board voted that "the cosmetics and fragrances employees are a readily identifiable group who share a community of interest among themselves." The 5th Circuit upheld that ruling last year, and the Supreme Court declined to hear an appeal on Monday.

Opponents of the Specialty Healthcare ruling hope that President Donald Trump's appointments to the National Labor Relations Board will cause the panel to rescind that standard in future cases. But it's unclear how that would affect smaller bargaining units that have already been approved.

The UAW criticized anti-labor Republicans and outside groups for casting doubt about the future of the Volkswagen factory if the union won a plant-wide vote in 2014. The workers ended up voting 712-626 against UAW representation, and the union has ruled out seeking another election.