BOSTON — On the dais in a Hynes Convention Center ballroom here on Saturday, retiring Rep. Barney Frank (D) sat scowling, eyeing the time, next to his likely successor, Joe Kennedy III, who smiled widely.

Frank was about to receive an award at the Massachusetts Teachers Association annual delegates meeting, and MTA President Paul Toner was introducing the 16-term Member to the few hundred attendees. He recalled some of Frank’s more blunt comments over the years to peals of laughter from everyone — except the Congressman.

It was a stark contrast between a 72-year-old who begrudgingly goes through the motions of local politics but still relishes a fight and a 31-year-old who won’t face much of one to come to Congress.

Kennedy, sporting a dark suit, blue shirt and green and gray tie, exuded ebullience at the pomp and circumstance of the event.

Taking the podium, Frank, the co-author of the marquee Wall Street reform law, noted the recent news that a big bank had lost at least $2 billion in risky trades.

“I had to be careful this week with regard to the news of JPMorgan Chase,” Frank said. “There is this lie everybody tells: ‘Oh, I don’t like to say I told you so.’ Well, of course, we all like to say, ‘I told you so!’ It is one of the few pleasures that improves with age.” The audience roared its approval.

Noting his retirement from the 4th district, Frank pledged to stay active in the public debate.

“I guess it’s going to be a transition,” he said. “People were talking about whether I would suffer fools. Now I get to the point where I can focus on what I most want to do, which is to make fools suffer,” he said, his throaty voice increasing in intensity.

The crowd, delegates of the 110,000-strong union, ate it up. And Frank acknowledged the young attorney on the dais with him. “I am very confident that Joe Kennedy will be representing the people that I have represented with great skill and great passion,” he said.

It was a passing of the torch, of sorts. Kennedy faces no real opposition in his bid to succeed Frank in Congress. The announcement that Kennedy, then a local assistant district attorney, would run for office cleared the Democratic field of any serious contenders.

Kennedy, the son of  former Rep. Joe Kennedy (D-Mass.) and the grandson of the late Sen. Robert Kennedy (D-N.Y.), raised a whopping $1.3 million in the first quarter of this year. He faces token opposition from Republicans, not because the potential candidates aren’t serious but because he is such a formidable candidate.

He’ll be on the ballot in November in the Democratic-leaning district facing off against either Sean Bielat, the 2010 GOP nominee for the district, or psychiatrist Elizabeth Childs, who served in former Gov. Mitt Romney’s (R) administration.

Bielat, a former Marine and businessman, has the edge because he has the support of many activists across the district. But he lost to Frank in the GOP wave year of 2010 by 11 points and will probably lose by more this cycle. Republicans hope to emphasize that Bielat, married with children, is someone who can understand the everyday concerns of voters better than his opponent.

But Kennedy, just by virtue of his last name and his charisma, probably has already won that battle.

“We certainly feel confident” in this race, one Democratic insider said. “Kennedy is getting a ton of support and it’s not just money.”

Democratic consultants in the state have been impressed with how hard Kennedy has been working, the fact that he doesn’t seem to be taking anything for granted and how many events he shows up at.

Kennedy later spoke to the MTA, hitting all the right notes. He talked about the importance of education and his time as a teacher in the Peace Corps. He didn’t have the polish or public speaking skills of a longtime pol, but the audience embraced him warmly.

“With all my heart and soul, I will defend public education,” he said to applause.

As Kennedy speed-walked out of the ballroom on his way to a packed day of events, he was mobbed like a Hollywood celebrity, with people clamoring to shake his hand. The president of the Newton Teachers Association — one of the largest cities in the 4th district — pledged his support to Kennedy.

“I shook your dad’s hand the day he was sworn in,” one woman said, smiling as she grasped the younger Kennedy’s palm.

“Good luck, Joe!” another woman yelled out in a thick Boston accent.

“The best part about all of this is the people you get to meet,” Kennedy said earnestly in a short interview. “We are having fun.”

Asked after his speech if he enjoyed doing events like this, Frank growled: “No.”

“But,” he conceded, heading for the door, “they’re important.”