In most elections, a politician calling himself the Tea Party candidate would cheer Democrats, raising hopes that he would siphon votes from Republicans by attracting some of the disaffected anti-Washington, anti-Obama electorate.
But when the election is being held to fill a seat that was left vacant by the death of Senator Edward M. Kennedy, and the Tea Party candidate happens to be named Joe Kennedy, things get a little murkier.
Democrats here are concerned that some uninformed voters might confuse him for a member of the better-known, well-loved Kennedy clan, which he is not. And Mr. Kennedy’s libertarian positions make him even more of a wild card in the last days of the race: some could appeal to the right, like his call to abolish the federal Department of Education, while others could appeal to the left, like his call for immediately ending the wars in Iraq and Afghanistan.
The underfinanced, little-publicized campaign of Mr. Kennedy, 38, is not likely to get many votes on Tuesday. But if the race between the major-party candidates — Martha Coakley, a Democrat and the state’s attorney general, and Scott Brown, a Republican state senator — is as tight as some polls suggest, Mr. Kennedy could play a key role by drawing just a few percentage points from either of them.
The fate of the Democrats’ bill to overhaul the health care system, whose passage depends on their keeping the Massachusetts Senate seat, just might be decided by Mr. Kennedy, a little-known information technology executive from Dedham.
At a campaign event here on Thursday afternoon, Mr. Kennedy, who spoke at length about competing economic theories and seemed a bit bookish in his gray suit, black loafers and, at times, rimless glasses, did not look very much like someone who just might change the balance of power in the Senate. Only a dozen people showed up to hear him speak in a community room in the basement of a library here, and one man sat and read a newspaper for almost the entire time.
But in an interview afterward, Mr. Kennedy said he had been deluged with e-mail messages from supporters of Mr. Brown, urging him to drop out of the race because they fear he could dilute the Republican vote, thus enabling the health care bill to pass.
“They say, ‘He’s taking votes from Scott Brown!’ ” Mr. Kennedy said. “And I say: ‘Well, actually that’s not true. Scott Brown and Martha Coakley are taking votes from Joe Kennedy!’ ”
Some aides to the other candidates believe that Mr. Kennedy may end up drawing nearly evenly from both sides. Ms. Coakley insisted that he get to participate in all the debates, clearly showing all who watched that this Joe Kennedy (Joseph E. Kennedy) was not the former congressman and nephew of the late Senator Kennedy (Joseph P. Kennedy II), who has endorsed Ms. Coakley.
Andrew E. Smith, the director of the University of New Hampshire Survey Center, said that Mr. Kennedy drew 5 percent of the vote in the latest poll he conducted for The Boston Globe, but that in the past, third-party candidates had often done better in polls than at the ballot box.
“If he draws from anybody, my sense is that he draws probably a little bit more from Brown, the protest vote,” Mr. Smith said.
But Mr. Kennedy said that if anything, he believed that more of his support was coming from Democrats, who like his opposition to the war and to the Defense of Marriage Act. And he said that as someone who was a Tea Party protester before deciding to run for office and who has the support of some of the local Tea Party groups, he regretted that many national Tea Party groups were now planning to support Mr. Brown.
He noted that while Mr. Brown had vowed to be the vote to stop the Democrats’ heath care bill in its tracks, Mr. Brown voted for the Massachusetts law to extend health insurance that was passed under another Republican, Mitt Romney.
“I’m a lot more hard-core against health care than Scott is: Scott voted for RomneyCare,” he said. “But those people who are against ObamaCare are not throwing their vote to me in any way shape or form.”
Indeed, FreedomWorks, a conservative organization led by former Representative Dick Armey that supports and organizes Tea Party rallies, is planning to begin a get-out-the-vote effort in Massachusetts this weekend — to help Mr. Brown.
Mr. Brown spent the day in Boston, attacking Ms. Coakley’s national security credentials and statements as “troubling.” Ms. Coakley discussed economic issues in New Bedford, suggesting that Mr. Brown would continue Republican tax policies that cost jobs.
Both are calling in bigger guns. President Obama recorded a television commercial for Ms. Coakley, and she plans to campaign Friday with former President Bill Clinton and Senator John Kerry. Mr. Brown, meanwhile, plans to campaign in Boston on Friday with former Mayor Rudolph W. Giuliani of New York.