Former Newton Mayor Setti Warren is being remembered as a joyous presence who infused the often cynical business of politics with a potent sense of optimism before his death last weekend at the age of 55.

“Even when everyone else is telling you how broken our politics are, how distrustful we should be of one another, how our system isn’t built to create good outcomes in politics, Setti was the kind of guy that made you believe it actually could be,” said Alex Goldstein, CEO of the communications firm 90 West.

Goldstein, who first met Warren in 2006 and later advised Warren on a volunteer basis as he campaigned to become the state’s first popularly elected Black mayor in 2009, also described Warren as having “the most explosive, contagious laugh” he’s ever encountered.

“You would do anything to hear it,” Goldstein added. “And so, people would sort of go out of their way to make jokes with Setti so they could just hear him laugh, because it was that good of a laugh. You could hear a Setti laugh from, like, the other end of a convention center. You knew that Setti was in the room.”

Warren had spent the past three decades playing various roles in local, state and national politics. Before he became mayor of Newton, he worked for President Bill Clinton as a campaign staffer and in the White House. He later worked for then-Sen. John Kerry’s 2004 presidential campaign and as a Senate staffer for Kerry. Kerry and his wife, Teresa Heinz, are the godparents of Warren’s daughter, Abigail.

Warren served as the mayor of Newton from 2010 to 2018, two terms during which he contemplated statewide offices. In 2011, Warren announced that he was running for the U.S. Senate seat then occupied by Republican Scott Brown, but later dropped out. Brown subsequently lost to Elizabeth Warren. In 2017, Warren announced a bid for governor but dropped out before the Democratic primary.

Most recently, Warren worked for Harvard. He had previously led Harvard’s Shorenstein Center on Media, Politics and Public Policy and was director of the Kennedy School’s Institute of Politics at the time of his death. Harvard announced his death on Sunday afternoon. No cause of death has been identified.

Former Massachusetts Gov. Deval Patrick worked with Warren during his governorship and later crossed paths with him at Harvard University’s Kennedy School, where Patrick was co-director of the Center for Public Leadership.

“I think he’ll be remembered as one of the rare public leaders who brought kindness, caring and a love for those he served to the role of public service,” Patrick said of Warren. “And he did it without embarrassment or, you know, shame, or being maudlin or anything like that.

“He was joyful about his politics and his service, and he had ambitions for others to bring that same joy and focus on the people served to politics in Massachusetts and beyond,” Patrick added.

Layla Chaaraoui, a senior at Harvard College who is active in the Institute of Politics, praised Warren’s stewardship of that institution in an email to GBH News.

“He created spaces for meaningful dialogue — as a moderator, mentor, and friend — and inspired generations of students to serve with empathy, courage and purpose,” Chaaraoui said. “His legacy of leadership, kindness and impact will continue to guide the IOP community for years to come.”

One member of Massachusetts’ congressional delegation, Rep. Jake Auchincloss, said he was inspired by Warren’s mayoral run when Auchincloss later made his own bid for Newton City Council. Asked what Warren’s legacy will be in Newton and elsewhere, Auchincloss didn’t hesitate.

“A good man, a good mayor, and somebody who combined charisma with competence,” Auchincloss said. “Somebody who genuinely liked people, and they liked him in return.

That sounds trite, but so much of American politics now feels like we just don’t like each other very much. And every time Setti walked into a room, he was happy to be there. Every time he talked to somebody, he was happy to be talking to them. And that doesn’t mean that he didn’t have sharp and driven views on things, but he campaigned and he governed with this joy that made people want to be part of something bigger than themselves.”

Deborah Shah — a progressive organizer who served as Warren’s campaign manager during his 2009 mayoral run and his subsequent bid for Senate — recalled Warren as a naturally gifted politician who adroitly made the switch from behind-the-scenes work as an aide to a star turn as the candidate.

“It was wonderful,” Shah recalled. “He was the best candidate ever, from a campaign manager’s perspective. He was a great human being — you know, joyful, open, caring, really hardworking.”

In his 2009 campaign, Shah said, Warren personally knocked on more than 10,000 doors, giving him a chance to speak with a large cross-section of Newton’s approximately 90,000 residents face-to-face.

“He was tireless in that, and there were some great stories,” Shah said. “There were people towards the end of the campaign who’d come to the door and say, ‘He’s come! He’s here!’ Because it was a time where there wasn’t as much door knocking. It wasn’t as well known, especially at the local level. People didn’t do that. They stood out with signs on Saturday morning [instead].”

Goldstein, who says he served as a member of Warren’s “kitchen cabinet” during and after that first mayoral run, predicts that — had he lived — Warren would ultimately have made another run for elected office.

“Setti had everything, and I was among the many folks who believed that Setti had another exciting political chapter ahead of him,” Goldstein said. “He had sort of a tough roll of the dice with a couple of the offices that he had been interested in, but I don’t think there was anybody who thought we weren’t going to see him again and that he wasn’t going to have a lot more to contribute.

“So, it’s heartbreaking on a personal level — and I also feel like Massachusetts has lost a really impactful, decent, kind, humble, political servant, public servant that we could really use.”

Adam Reilly is a politics reporter and the host of GBH’s Talking Politics.