Updated with some content from the Associated Press.

The United Auto Workers on Wednesday called on Volkswagen to start bargaining with maintenance workers at the Chattanooga plant after the union won a federal ruling, but the carmaker said it's reviewing its options.

A National Labor Relations Board panel denied VW's request for a review of last December's election in which a small group of Chattanooga workers agreed to be organized by the UAW.

The panel, in a 2-to-1 decision, said VW raised "no substantial issues warranting review." It agreed with an earlier decision by the NLRB's regional director in Atlanta that the small size of the unit of maintenance employees satisfies its standards.

Mike Cantrell, president of UAW Local 42 in Chattanooga, said the NLRB supervised a fair election at the plant in which the skilled trades workers voted 108-44 to align with the union.

"We're glad to see the decision upheld and we look forward to meeting Volkswagen at the collective bargaining table in the near future," he said.

However, Scott Wilson, the VW plant's communications head, said Wednesday it had just received the NLRB decision and it's under review. He said the automaker is "evaluating our options."

VW had sought the NLRB ruling because it wanted an election of all the blue-collar employees at the plant, more than 1,300, and not just the skilled trades workers who repair and maintain the robots at the factory.

Chattanooga labor attorney Dan Gilmore said VW could choose to continue to press its case to the NLRB. The automaker would do so within the context of an unfair labor practice the UAW filed after the election because of VW's unwillingness to bargain with the union, he said.

Gilmore said he believes VW will most likely stay the course and refuse to bargain until getting a final decision relating to the unfair labor practice charge from the board.

If the NLRB decides against VW, the automaker could then take its case to a U.S. appeals court, Gilmore said.

Tennessee Gov. Bill Haslam, who has opposed the UAW's efforts at the plant, criticized the union's decision to seek last December's election when the company is dealing with the diesel emission issue that has engulfed the automaker.

Haslam asked if the UAW is "really concerned about the health and well-being of the company or are they more concerned about their own interest?"

But the UAW said the December election was unrelated to the diesel issue. The union said Local 42 asked VW to recognize the union in August 2015, a month before the emissions scandal was revealed.

The UAW had lost an election of the blue-collar workforce at the plant in February 2014 by a vote of 712-626. The December win was the UAW's first at a Southern auto plant owned by a foreign carmaker.

Gary Casteel, secretary-treasurer of the UAW, said the NLRB has clearly stated that it views the skilled trades election in Chattanooga as a legal and appropriate step toward meaningful employee representation.

"We hope Volkswagen's new management team will accept the government's decision and refocus on the core values that made it a successful brand — environmental sustainability and meaningful employee representation," he said in a statement.

The NLRB panel, in its ruling, said the maintenance employees are readily identifiable as a group. They share a community of interest under the traditional criteria — similar job functions, shared skills, qualifications, training and supervision separate from the production employees, it said.

Still, the dissenting board member said there's no centralized maintenance department, and that VW's operation has three departments — body weld, paint and assembly — which include members of production and skilled trades.

Staff writer Andy Sher contributed to this story.

Contact Mike Pare at mpare@timesfreepress.com or 423-757-6318.