CHATTANOOGA, Tenn. — In a defeat for organized labor in the South, employees at the Volkswagen plant here voted 712 to 626 against joining the United Auto Workers (UAW), even though the company did not oppose the unionization drive.

The UAW’s loss — in what was one of the most closely watched unionization votes in decades — is expected to slow, perhaps stymie, the union’s plans to organize other auto plants in the South. Two other German-owned plants, Mercedes-Benz in Alabama and BMW in South Carolina, have been among its top targets.

The loss now makes it even harder for the union to recruit members at those other factories, a key priority of departing UAW President Bob King. He has said that the union has no long-term future if it can’t organize the Southern plants.

“It is pretty devastating” for the union, said Kristin Dziczek, director of the labor and industry group at the Center for Automotive Research, an industry think tank in Michigan. “If this was going to work anywhere, this is where it was going to work.”

The vote this week came in a region that is traditionally anti-union, and as a result many said the UAW faced an uphill battle. The union saw the campaign as a vital first step toward expanding in the South, while Republicans and many companies in Tennessee feared that a UAW triumph would hurt the state’s welcoming image for business.

For the union, the effort occurred with one highly unusual — and highly favorable — circumstance. Unlike most American companies, Volkswagen did not oppose the unionization drive, pledging to remain neutral and in ways offering quiet support to the union.

Nevertheless, Republican politicians in Tennessee and some outside conservative groups made sure that the plant’s nearly 1,600 workers heard plenty of anti-union arguments.

Gov. Bill Haslam, a Republican, warned that auto-part suppliers would not locate in the Chattanooga area if the plant was unionized. Sen. Bob Corker, a Republican and former mayor of Chatanooga, said Volkswagen executives had told him the plant would add a new production line, making SUVs, if workers rejected the union. That was denied by a VW executive in Tennessee.

In a news conference and a series of interviews this week, Corker also asserted that a union victory would make Volkswagen less competitive and hurt workers’ living standards.

To step up the pressure, state Sen. Bo Watson, who represents a suburb of Chattanooga, warned that the Republican-controlled Legislature was unlikely to approve further subsidies to Volkswagen if the workers embraced the UAW, a threat that might discourage the company from expanding.

Volkswagen officials had urged “third parties” to remain neutral and stay out of the unionization battle. Grover Norquist, the anti-tax crusader, helped underwrite a new group, the Center for Worker Freedom, that put up 13 billboards, warning that the city might become the next Detroit if the workers voted for the UAW.

Volkswagen publicly did not oppose the UAW, partly because its officials were eager to create a German-style works council, a committee of managers and blue-collar and white-collar workers who develop factory policies on issues like work schedules and vacations.

Volkswagen, which has unions and works councils at virtually all its 105 other plants worldwide, views such councils as crucial for improving morale and cooperation and increasing productivity.

Many legal experts say it would be illegal to have a works council unless workers first voted to have a union. VW wanted Chattanooga to be the first plant in the United States to have a works council.

Gary Casteel, a UAW regional director who headed organizing efforts at the plant, hinted that the union may challenge the election results with the National Labor Relations Board.

“We think that it’s unfortunate that there was some outside influence exerted into this process,” Casteel said Friday night. “There are still some issues that have to be sorted out about this election, and we’ll let the people that do that evaluate the impact of others and whatnot further down the road.”

Material from The Associated Press is included in this report.