NEWTON (AP) — Joseph Kennedy III officially launched his campaign for the U.S. House on Thursday, embracing his family’s legacy in Massachusetts while also acknowledging that name alone will not assure him electoral success.

WBZ NewsRadio 1030′s Carl Stevens reports

“You’ve got to earn it,” Kennedy told reporters after greeting commuters at a train station in Newton, the first of several stops the Democrat planned to make in the reconfigured 4th Congressional District.

Read: Keller @ Large: Kennedy Name Not A Guarantee Of Success

“You’ve got to go out every day and talk to people, listen to their concerns, shake more hands, knock on more doors, take more phone calls.”

Kennedy, 31, is seeking the seat held by the retiring U.S. Rep. Barney Frank.

He released a three-minute video announcement on his website early Thursday before heading out on the tour that also will take him to the largely blue-collar communities of Milford, Attleboro, Taunton and Westport.

WBZ NewsRadio 1030′s Ben Parker reports on Democratic field

The first stop was on largely friendly ground in the upscale Boston suburb.

The redheaded son of former U.S. Rep. Joseph P. Kennedy II and grandson of the late Robert F. Kennedy frequently flashed a trademark Kennedy-esque grin as he strode along the train platform and chatted up riders waiting for inbound trolleys to the city.

“We’ve got a long way to go,” he told one man who then remarked that a friend knew one of Kennedy’s uncles, a nod to the many personal and political connections Massachusetts voters still have toward the family.

“He’s a Kennedy — no coat,” pointed out one older supporter who wore a Kennedy sticker. John F. Kennedy famously doffed his overcoat on a bitterly cold day during inauguration ceremonies in Washington, D.C., in 1961.

The late president’s great-nephew wore a dark blue suit and tie on a chilly but not unseasonably cold morning more than half a century later.

Kennedy’s official announcement was largely a foregone conclusion after he said last month that he was forming an exploratory committee to run for the seat.

He later resigned his job as a prosecutor in Middlesex County and moved from Cambridge, outside the 4th district, to Brookline, within the district.

He has already been endorsed by two major labor unions and a recent poll showed him with a commanding early lead over Republican Sean Bielat, who lost to Frank two years ago and is running again.

While the Kennedy name remains a powerful force in the state, Republicans are quick to point to U.S. Sen. Scott Brown’s surprising victory over Democrat Martha Coakley in the special election that followed U.S. Sen. Edward Kennedy’s death in 2009.

Edward Kennedy had held the seat for nearly a half century, and John F. Kennedy had held it before his brother. The Republican Brown carried several of the communities in the 4th district in the special election.

“I just think the Kennedy name is not enough to elect somebody,” said Mary Thomits, a retired teacher from Brookline who said she “shocked” Kennedy when he introduced himself to her Thursday at a diner near the transit station by telling him that she did not think he was qualified to run.

Thomits, who said she was an independent but planned to vote for Bielat, said she was turned off by the fact that Kennedy was being opportunistic by changing his residence to run in the district. “I think he’s just riding on his name,” she said.

WBZ-TV’s Sera Congi reports:

But Mike Grossman, a 56-year-old Newton resident, said he welcomed Kennedy’s candidacy. Though an independent who had voted for Republicans in the past, Grossman said the Kennedy family had a “legacy” that was positive for the state.

Kennedy defended his qualifications for office, pointing to his experience as a volunteer in the Peace Corps, as legal aid attorney and prosecutor as evidence of his concern for the disenfranchised.

WBZ NewsRadio 1030′s Lana Jones reports from Attleboro

“I think I’ve had an opportunity over the course of my life to see what happens to people who are playing against a stacked deck,” he said.

Kennedy said he was proud of his family’s long record of public service, but his only specific reference to a family member during his first campaign exchange with reporters came on a question about the current partisan deadlock in Washington. He remarked that Edward Kennedy, while being known as a “liberal lion,” was also able to reach across the aisle and forge strong working relationships with Republicans.

“One of his best friends in the Senate was (Utah Republican) Orrin Hatch,” he said.

Copyright 2012 The Associated Press.