Joseph P. Kennedy III is far out front of his possible Republican opponent in the contest for the congressional seat being vacated by Barney Frank, although the 31-year-old scion of the famed political dynasty has not yet officially entered the race, a new poll has found.
Kennedy, the grandson of Robert F. Kennedy who recently left his job as a prosecutor to consider a run, would defeat Republican Sean Bielat, 36, by a 2-to-1 margin, according to results released Thursday night from the poll conducted for UMass Lowell and the Boston Herald.
Bielat said in a phone interview Thursday night that he was not concerned about the early numbers.
“It’s consistent with everything we know about the race, which is that nobody knows who this guy is, they just know his last name,” he said of Kennedy.
Kyle Sullivan, a spokesman for Kennedy, said in an email Thursday night that the poll numbers were premature. He declined comment when asked if Kennedy was any closer to officially declaring his candidacy.
“If Joe runs he is going to work hard to earn every vote,” Sullivan said. “He has been traveling across the district talking about the issues that are important to the people of the 4th district -- creating new jobs, providing better educational opportunities, and restoring common sense and fairness in Congress.”
The poll, which surveyed 408 voters in the fourth congressional district and has a margin of error of plus-or-minus 6.4 percentage points, also found that nearly three-quarters of the respondents had a positive view of the Kennedy family overall.
The numbers belie the fact that Bielat, a former program manager at the iRobot Corp. in Bedford who currently lives in Norfolk, emerged in 2010 as the toughest challenger to Frank’s incumbency in nearly two decades before ultimately losing the race by 11 percentage points.
Kennedy, who is also the son of former Congressman Joseph P. Kennedy II, could benefit from his family’s name recognition in a head-to-head matchup with Bielat, the poll found.
Twenty-eight percent of respondents said his pedigree would make them more likely to vote for him, while 15 percent said it would make them less likely to support him, and 56 percent said it made no difference.
At the same time, however, 34 percent of respondents said the Kennedys have too much influence on state politics, while 49 percent said the family has ‘‘about the right amount of influence,’’ and 8 percent said they do not have enough, the poll found.
Bielat took aim at the Kennedy legacy last month when he announced that he was launching his second campaign for the seat.
‘‘Nobody should expect to succeed in this country by virtue of their birth,’’ Bielat told a roomful of supporters. ‘‘I don’t know why you’re applauding. Do you think that refers to someone?’’
Bielat will face at least one primary challenger — Elizabeth Childs of Brookline — for the Republican nomination.
Though Bielat raised money from GOP donors across the country in 2010 who were energized by the possibility of unseating Frank, a liberal stalwart, 55 percent of the poll respondents said they had never heard of him.
“The last time when I started [name recognition] was at zero,” Bielat said, adding that there are many new voters in the redrawn district.
“I can’t get too upset about it,” he said of the overall numbers. “[The results are] not surprising and not very meaningful, frankly.”
Only 7 percent said that Kennedy’s name was unfamiliar, though 14 percent of respondents said they had trouble distinguishing between him and his father.
While Kennedy has yet to announce whether he intends to run on the Democratic side, other contenders have announced that they are seeking the party’s nomination, including Paul Heroux, an Attleboro consultant, and Herb Robinson, a Newton software engineer.
The poll also touched on the race between US Senator Scott Brown, a Republican, and his probable Democratic opponent, Elizabeth Warren, a Harvard law professor.
Fifty-three percent of respondents held a favorable view of Brown, compared with 33 percent unfavorable, while 36 percent had a favorable view of Warren, compared with 19 percent unfavorable.
Twenty-nine percent of respondents said they had never heard of Warren.
And the man who tapped her to help form the federal Consumer Financial Protection Bureau is popular in the district, according to the poll — 59 percent of respondents viewed President Obama positively, while 38 percent held an unfavorable view of him.
The poll was conducted under the direction of independent survey researcher Mike Mokrzycki, former head of polling for the Associated Press, the University of Massachusetts said.