A NEW, little-known generation of Democratic leaders is stepping forward as the 1992 presidential race finally gets under way in earnest across the United States.Political analysts here in New Hampshire, site of the nation's first presidential primary, say the Democratic fight for the presidency appears highly unpredictable and includes some underlying dangers for the Republican White House. First, unlike any other presidential campaign in modern times, there is no clear-cut front-runner for the Democratic nomination. Whether it was Lyndon Johnson in 1968 or Michael Dukakis in 1988, there has always been a favorite here in New Hampshire. Second, most of the Democrats running in 1992 will be fresh young faces unknown to most Americans. While they lack a national base, these candidates will be harder for George Bush to tar with the old label of "tax-and-spend Democrats" who are soft on crime and weak on defense. "We have an opportunity here," says a Democratic leader in New Hampshire. "Republicans aren't going to be able to wrap themselves in a balanced-budget amendment even though they submit unbalanced budget after unbalanced budget." Now Republicans will be confronted with Democrats like Gov. Bill Clinton of Arkansas, a fiscal conservative. "They aren't going to be able to wrap themselves in a flag against [Sen.] Bob Kerrey [of Nebraska] because he's got all the medals. They don't come any truer, real-life nephew of Uncle Sam than Bob Kerrey," says the Democrat, who asked not to be identified. Senator Kerrey, a Medal of Honor winner, is scheduled to declare his candidacy for the White House on Sept. 30. The Democratic field continues to expand. Sen. Tom Harkin of Iowa, Gov. L. Douglas Wilder of Virginia, and former Massachusetts Sen. Paul Tsongas have already declared. Gov. Bill Clinton of Arkansas may soon follow, along with Kerrey and former California Gov. Jerry Brown. Rep. Dave McCurdy of Oklahoma is talking with friends about a campaign, as is the Rev. Jesse Jackson. A long-shot, former Irvine, Calif., Mayor Larry Agran already has entered. Gov. Mario Cuomo of New York remains a possible contender. Analyzing the growing field, G. Donald Ferree, associate director of the Institute for Social Inquiry at the University of Connecticut, says that Governor Cuomo and the Rev. Mr. Jackson "hover as presences" over the campaign. Either man could leap into the race at the last moment and still have a major impact. However, Mr. Ferree says one of the most intriguing and surprising performers in this field could be former Governor Brown. An ABC News poll of 1,233 adults nationwide on Sept. 13-15 found that 24 percent of Democrats surveyed said they would support Brown in a primary. The next highest was Governor Wilder, with 13 percent. Governor Clinton had 7 percent, Kerrey 4 percent, Tsongas 4 percent, and Senator Harkin 3 percent. While such a poll has little significance at this early stage, it may indicate an inclination among many Democrats to try someone who is anti-Washington and willing to explore new ideas, such as Brown. As Ferree says: "Brown is not a conventional politician." He blends a "New Age way of looking at the world" with a sometimes "strange set of issues." He continues: "People may find that repellent, they may find that attractive. But it is certainly different. That helps him stick out from the field, which has been relatively gray. It also means that if Democrats are coming to the notion that the way to beat Bush is with something unconventional ... that tends to work to his advantage." A leading Democrat in New Hampshire agrees that in the early weeks, Brown may enjoy a boomlet here. He says those who know Brown often have mixed feelings: "It isn't like; it isn't dislike. It is sort of wonderment at what he is doing and saying." Brown's flamboyant, anti-establishment style could monopolize media attention, one Democrat says, though he observes that if the focus shifts from personality to issues, Brown loses. Wilder, as America's first and only elected black governor, also could be a media darling, Democrats here suggest. Among the other candidates: Harkin, with strong labor backing, may have an organizational advantage over the others. Kerrey could do well among thousands of independent voters, much as Gary Hart did so successfully in 1984. Clinton, as a fellow Southerner, will be fighting Wilder for moderate and conservative voters. Wilder will emphasize economic issues, while Clinton pushes education. Tsongas remains a wild card with his business-oriented plan to spur economic growth, Democrats say.