DETROIT (Reuters) - The United Auto Workers union will launch a campaign aimed at organizing the U.S. manufacturing plants of Asian and German automakers in January, the union's president told an industry publication on Wednesday.

UAW President Bob King told Automotive News in an interview that the union had sent letters to the chief executives of automakers with U.S. operations telling them that the union wanted to cooperate with them and to organize their plants.

The UAW, which represents workers at the U.S. automakers, has not succeeded in organizing workers at U.S. plants run by Toyota Motor Corp or Nissan Motor despite efforts that go back to the 1990s.

Japanese, Korean and German automakers have all opted to open plants in recent years in southern U.S. states where the union faces a tougher struggle to organize workers.

Earlier this year, the UAW had organized protests of Toyota dealerships after the Japanese automaker decided in the spring to close its assembly plant in Fremont, California.

That plant, which had been run as a joint venture with General Motors Co, was represented by the UAW.

King told Automotive News that the pickets outside Toyota dealerships were not advancing the union's goal.

"We said we were going to be the UAW of the 21st century and didn't feel like that was accomplishing that goal," King told Automotive News.

King told the trade publication that the union would hold a news conference in January to launch its organizing drive.

He did not, in the interview, name the automakers that the union would target. The union had announced its intent to ask Asian and German automakers to allow organizing votes at their plants in August.

Toyota, Nissan, Honda Motor Co, Hyundai Motor, Daimler AG and BMW all run assembly plants in the United States.

None of those plants are unionized.

King, who took over the top job at the UAW last summer, has made it a priority to recruit new members and stem a long-running decline in the union's power.

The UAW now represents just under 400,000 members, down from a peak of nearly 1.5 million in 1979 when U.S. automakers commanded a larger share of the market.