With little to distinguish them ideologically, the first official debate among the Democratic candidates in Massachusetts’ Senate special election boiled down to a discussion between the merits of voting for an insider with a long political résumé or an outsider unfettered by special interests.The two first-time candidates, wealthy businessman Stephen Pagliuca and Alan Khazei, founder of community service program City Year, gave little indication, however, that they have the political chops to threaten veteran officeholders state Attorney General Martha Coakley and Rep. Mike Capuano.Monday night’s hourlong debate was marked by innumerable references to the late Sen. Edward Kennedy (D), whom the four candidates are seeking to succeed. It touched on everything from health care to Afghanistan to immigration but placed a special emphasis on the economy and jobs. Moderator Peter Meade of the Edward M. Kennedy Institute for the United States Senate tried but failed to draw out much dissension among the candidates, who stuck mostly to generalizations and refused to be pinned down when asked to make choices about policy priorities.Pagliuca, managing director at Bain Capital and a co-owner of the Boston Celtics, was especially vague in his policy pronouncements, and at times seemed uncertain in his delivery. Khazei, meanwhile, struggled to give concise responses, repeatedly exceeding his given time limits.If Coakley came off as the most polished of the four candidates, Capuano was the most passionate, displaying a force of conviction in his support for a “robust public option— in the proposed health care overhaul legislation and opposition to sending more troops to Afghanistan. He repeatedly emphasized his experience in Congress and at one point offered to instruct his three opponents “when they want to know how Washington works.—Coakley, the frontrunner in the Democratic race according to early polls, demonstrated a strong grasp of an array of policy issues and indicated she would take a slightly more moderate policy approach than Capuano, including considering a health care overhaul that includes a public insurance option that states could opt out of.Khazei and Pagliuca both pointed to their refusal to accept political action committee and special interest money as a sign they would bring a better kind of representation to Washington. Khazei repeatedly pointed to corporate lobbying as the source of legislative ills, generating too many earmarks in the stimulus package and beating back efforts to obtain universal health care coverage. But neither gave much indication beyond that of how they would combat the influence industry once they got to Washington.Whoever wins the Democratic primary on Dec. 8 will be a strong favorite to win the Jan. 19 general election, given the state’s heavy Democratic lean. State Sen. Scott Brown is expected to win the Republican nomination with little opposition.The winner of the general election will succeed interim Sen. Paul Kirk (D), a longtime Kennedy associate and former Democratic National Committee chairman who was appointed by Gov. Deval Patrick (D) and sworn in Sept. 25, exactly a month after Kennedy died of cancer.