Chris Hansen-Nelson's gray hair stands out in this crowd. Out of the six hundred or so Bill Bradley volunteers staying at the Nashua Boys and Girls club tonight, there are only a handful of veteran campaigners. Nelson came of age in 1972, the first year in which 18-year-olds were allowed to vote. "We were all pretty jazzed about that," he says. "We were old enough to die, and now we were also old enough to vote." In his salad days, he says, he participated in many political events, but they were mostly of the anti-establishment, down-with-the-government, burn-Nixon-in-effigy sort.