By Bernie Woodall DETROIT (Reuters) - The United Auto Workers union said on Thursday it will announce as soon as next week a plan to organize workers at the Daimler AG Mercedes-Benz plant in Alabama. Gary Casteel, the union's newly elected secretary-treasurer, said the UAW will reveal its plan for workers at the Daimler plant in Tuscaloosa, Alabama "probably in the coming week." New UAW President Dennis Williams said Casteel, 56, will lead the union's efforts to gain membership by organizing foreign automakers, which are primarily located in the South. Casteel did not offer details of the UAW's plan in Alabama. Sonny Hawthorne, a leading anti-UAW worker at the Mercedes-Benz plant, told Reuters the union would have the support "of 25 to 30 percent (of plant workers), at the most" if a vote were held today. Hawthorne said he was confident the union's efforts to organize the factory will fail. Earlier this week, the UAW reacted to reports that pro-union workers in Alabama want the UAW to stop organizing efforts because they have gone on too long without success. "They want to have an election right away," Williams told reporters on Monday. "We perceive it that we have more building to do there." STRATEGY SHIFT AT VW, NISSAN, DAIMLER Casteel said the union is changing its strategy on how to organize workers in Alabama, as well as at the Volkswagen AG factory in Chattanooga, Tennessee, and the Nissan Motor Co <7201.T> plant in Canton, Mississippi. He said the union will continue to have active organizing efforts at all three Southern plants. At the UAW convention this week, Frank Patta, general secretary of the Volkswagen AG global works council, vowed that the effort to organize Chattanooga workers would continue. The UAW has worked closely with German union IG Metall to organize the Mercedes-Benz and VW plants. In Mississippi, where most of the plant's workers are black, it has linked workers' rights to civil rights. "We have a bit of a different approach between the Nissan and the Volkswagen and Daimler cases," Casteel said, adding that the new approach would perhaps not have "as much confrontation as we’ve had in the past." He also said the union might spend less money on the campaigns. Casteel said the strategy shift is a reaction to anti-union groups and Republican politicians, who were successful in thwarting the UAW's efforts to win a vote among VW's Chattannooga workers in February. "The things that we were doing last year don’t work because of this dynamic that you didn’t have to deal with" in the past, Casteel said. "So, we’re re-evaluating where we’re at with all of them." The UAW wants to organize the foreign plants to increase its membership, which has fallen about 40 percent in the past decade to about 390,000. (Reporting by Bernie Woodall. Editing by Andre Grenon)