DETROIT (Reuters) - Volkswagen AG (>> Volkswagen AG) skilled trades workers at the company's lone U.S. auto assembly plant will vote on Dec. 3 and Dec. 4 whether to be represented by the United Auto Workers, the union said on Wednesday. Volkswagen, which had earlier been the most supportive of the UAW among foreign automakers with U.S. plants, fought the petition by the UAW for a vote of 165 skilled trades workers at the plant in Chattanooga, Tennessee.

The skilled trades workers maintain the production machinery at the plant that makes Passat sedans.

A VW spokesman in Chattanooga on Wednesday said the company "is reviewing the content" of the decision by an NLRB regional director and "considering its options." Further, VW said it does not want workers at the plant to be separated into fragmented representation groups.

In February 2014, the union lost an election to represent all hourly production workers at the plant by a vote of 712-to-626.

Federal law allows a portion of a work location to be represented by a union, the UAW said.

The tone of UAW statements on VW and the plant workers in Chattanooga has taken a turn since the union was working with VW more closely in 2014.

Gary Casteel, UAW vice president and head of its organizing effort at foreign-owned plants, said, "Volkswagen’s attempt to sidestep U.S. law (by opposing the vote) was a waste of employees’ time and energy, and a waste of government resources."

The UAW represents workers at the three Detroit automakers: General Motors Co (>> General Motors Company), Ford Motor Co (>> Ford Motor Company) and Fiat Chrysler Automakers  (>> Fiat Chrysler Automobiles NV).

(Reporting by Bernie Woodall; Editing by Jonathan Oatis)

By Bernie Woodall