Calling him a candidate most likely to keep America strong, Teamsters union President William McCarthy announced Monday the nation's largest labor organization is endorsing Vice President George Bush, but not his running mate, in the presidential election. About 22,000 of the union's 1.7 million members voted over the last month, with Republican Bush edging Massachusetts Gov. Michael Dukakis by about 4 percentage points. The breakdown was 50.2 percent for Bush, 46.4 percent for Dukakis and 3.4 percent undecided or voting for other candidates. McCarthy stressed in several remarks that the Teamsters' endorsement is for Bush only, not GOP vice presidential nominee Sen. Dan Quayle of Indiana or the administration of President Reagan. "I'm not interested in Quayle or am I interested in Reagan or anybody else," McCarthy said.