DETROIT, April 23 (Reuters) - United Auto Workers (UAW) President Shawn Fain is moving quickly in the union's sweeping organizing push at U.S. plants across more than a dozen automakers after clinching an historic victory at a Volkswagen plant in Tennessee.

"The win Friday breathes a lot of life into the organizing campaign everywhere," Fain told Reuters on Tuesday. "We're moving as fast as we can."

The UAW has targeted organizing the nonunion U.S. plants of 14 automakers, setting aside $40 million for the effort.

VW was viewed by many industry analysts and officials as the easiest nonunion factory to organize given the company's strong union relations in Germany.

At Mercedes, where about 5,000 workers are scheduled to cast ballots in a UAW vote next month, the pushback against the UAW has been stronger.

In a letter to employees in January, the automaker said the union organizers "cannot guarantee you anything" and that some workers had said no to unionization because of Mercedes' competitive pay and benefits. Mercedes has said it respects workers' right to organize.

Fain said he doesn't view winning at Mercedes as a tougher battle than VW. "It's all the same. Workers either want justice or they don't," he said.

While the VW vote was historic - the 73% victory came after two previous failed attempts - bigger targets are ahead, including Toyota and electric vehicle maker Tesla.

Once 30% of eligible workers support joining the union, the UAW considers an organizing campaign at that facility publicly launched. The UAW typically does not call for an NLRB vote until 70% of eligible voters at a facility have signed cards of support.

None of Tesla's U.S. facilities have so far crossed that 30% bar, according to disclosures made by the union.

"Winning at Tesla would be the biggest possible victory you could get for the entire U.S. labor movement, never mind the auto industry," said John Logan, labor professor at San Francisco State University.

The union has said that workers at two other plants in the U.S. South - a Hyundai plant in Alabama and a Toyota parts factory in Missouri - have also launched organizing campaigns, with 30% of employees signing cards of support.

Fain declined to comment on what other factories are close to reaching the 30% threshold, or if a vote at the Toyota parts factory or Hyundai plant can be expected in the coming months.

The UAW also has seen a lot of momentum at a Toyota plant in Georgetown, Kentucky, an outside spokesperson for the union said.

A few months after being elected president in March 2023, Fain negotiated new labor deals with the Detroit Three automakers, General Motors, Ford and Stellantis .

He clinched deals for union workers at the companies that included a 25% pay raise over the life of the 4-1/2 year contract, the return of cost-of-living wage adjustments and improved benefits for retirees.

Workers at Volkswagen said these wins were essential to winning support in Tennessee.

"Bargaining that record contract was a massive reason why we're standing where we are right now," Fain said. (Reporting by Nora Eckert, editing by Ben Klayman and Michael Erman)