HE snared the 1992 Democratic convention for the Big Apple. He has taken a leading role in urging Washington, D.C., to restore aid to the cities.Yet New York City Mayor David Dinkins is viewed by many voters here as much more of a caretaker and conciliator than a long-range planner with a 21st-century vision for the city. In part, it's the political nature of the job. "There isn't much political capital for a mayor to engage in long-term planning - if you can do it NOW, you get the points for it," says Ester Fuchs, a political scientist at Barnard College and author of the forthcoming book, "Mayors and Money." Also, Mayor Dinkins has faced an unusually tough fiscal challenge. He has cut spending, hiked taxes, and still hopes for labor "givebacks." His newest revision of the city's four-year financial plan is due this week. The business community wants it to include a tax freeze and a cut of 30,000 municipal workers. "We'll see very soon whether this administration is thinking about the long-term or the short-term," says Citizens Budget Commission president Raymond Horton. "If they view the work force as a huge block of people who can't be reduced ... and made more productive, then they're saying, 'We're going to continue what we've done in the past. Beset by day-to-day demands, Dinkins has only recently focused on some of his campaign pledges. Though so far unable to close large city shelters and welfare hotels for the homeless as promised, he has proposed building 20 to 30 small shelters for single adults in varied neighborhoods. The Not-in-My-Backyard (NIMBY) outcry was quick and loud but not universal. "I think his plan is right on target," says George Richardson, a former heroin addict and strong advocate of more direct social-service help in the neighborhoods. "We all have to make sacrifices and cooperate or the city simply isn't going to work." Dinkins insists that strong protection for the environment is both morally right and a money-saver. He says the city's efforts to protect the source of its drinking water have saved taxpayers $5 billion. He is switching to natural gas for the city's car fleet and has recently launched an effort to use treated sewage or sludge, usually dumped in the ocean, as fertilizer in city parks. The mayor is now weighing the possible creation of two new public authorities - one for management of solid waste and the other for bridge and highway maintenance. To stem further exodus from the city of nonprofit groups - accounting for a full 10 percent of all jobs in the city - Dinkins recently offered to make available 20 floors of a private office building at a low rate with free rent for the first year. "That was leadership - it was a long-term, strategic thing to do," Fuchs says. She adds that New York City will survive its current economic crisis but is more concerned with Washington's abandonment of the cities. The city has lost $25 billion in federal aid in the last 10 years. "We can't be a great nation without great cities, and New York as the premier city of the country is the litmus test," she says. "If New York falls, it all falls." Dinkins, who held an urban summit here last fall to make just that case, is sure to be in the front lines when mayors and other supporters of cities march on Washington April 11.