(FORTUNE Magazine) – The Iowa caucuses won't kick off the 1992 presidential season for another 18 months, but a few early-bird Democrats have already visited the state to press the flesh of party faithful and other voters. Among them: Ohio Governor Richard Celeste, Colorado Representative Patricia Schroeder, and Virginia Governor Douglas Wilder. Are they presidential prospectors or mere visiting firemen? Says political consultant Ted Van Dyk: ''Any Democrat who goes to Iowa is probably testing the waters.'' The visitors aren't announcing their intentions. Celeste made an early bid for a spot on the national ticket in 1988 and soon faded. His deputy press secretary, Reuven Carlyle, said the governor's June trip to an Iowa Peace Institute debate was simply part of his job as chairman of the Democratic Governors' Association. But, adds Carlyle, ''that doesn't mean the ideas he had in 1988 won't be appropriate again.'' Schroeder also had big-ticket ideas in 1988. Is she about to give it another shot? Says her office: No decisions until the end of this year. But she's been quick to say yes to Democratic fund-raisers in Iowa City and Des Moines and speaking dates at two Iowa universities. The big speculation involves Wilder, the nation's first elected black governor, who spent two days in Iowa in June. He visited five cities, including Sioux City and Cedar Rapids, addressing fund-raisers and rallies -- and meeting babies (see photo). Like the others, Wilder declines to discuss his political plans. But Democratic and Republican party insiders believe Wilder's political ambitions stretch beyond the Virginia Statehouse. Says one: ''He's obviously running for something.''