Tributes poured in Monday as the Massachusetts political world mourned the death of John Walsh, a Democratic activist who helped get Deval Patrick elected governor and invigorated the party's progressive grassroots in the process. The former Democratic Party chairman was 65.

Walsh's death Monday was confirmed by the Mass. Democratic Party and the office of U.S. Sen. Edward Markey, where Walsh worked as chief of staff. Markey called Walsh "a political genius and a transformational figure in the history of Massachusetts movement building" and numerous mourners said Walsh's legacy will be the huge roster of young people he mentored and encouraged to become more involved in their communities and politics.

"John Walsh had a love of politics that was unmatched, which led to some of the most historic campaign wins in our state’s recent history. His legacy will live on in the many young political campaign staff he mentored and hired who are now running campaigns, working in government, or are elected officials themselves. He also will be remembered for his unrelenting efforts to bring new energy and people into the Democratic Party," current party Chair Steve Kerrigan said.

An Abington selectman and insurance salesman who had been involved in campaigns for years, Walsh was a key architect of Deval Patrick's successful 2006 run for governor. The mostly-unknown Milton lawyer scored a stunning win over two longer-established Democrats and a well-financed Republican officeholder with Walsh as campaign manager. He was propelled to cult hero status among many of the party faithful for having awoken the party's grassroots to boot Republicans from the governorship after 16 years.

Walsh then served as chair of the Massachusetts Democratic Party from 2007 to 2013, or for most of Patrick's two terms as governor.

He was also at the helm of Markey's 2020 reelection, which saw the longtime member of Congress successfully define himself as a progressive champion to endear himself to young, liberal voters and fend off a primary challenge from U.S. Rep. Joseph Kennedy III. After that campaign, Walsh moved inside government and took the job of being Markey's chief of staff.

Here is a portion of the tributes and remembrances that circulated Monday, some have been condensed:

Former Gov. Deval Patrick, on X: "Today we lost the incredible John Walsh. His memory lives forever in the legions of us he inspired, taught and cared about."

U.S. Sen. Ed Markey: "John Walsh was a political genius and a transformational figure in the history of Massachusetts movement building. He believed in the extraordinary capacity of ordinary people. He knew that the path to justice runs through the kitchen tables, civic centers, schools, and town squares in every corner of Massachusetts and our country. John was a visionary who saw talent in everyone, and his genius was hands-on. We see it in the miles of knocked doors, hands he shook, coffee meetings he took, and minds he opened. He didn’t just see ways to change the world; he dedicated his life to changing it himself. He made time for everyone, shared selflessly of his wisdom and experience, and redefined leadership for Massachusetts candidates. John’s legacy will be in the young people he mentored and brought into public service, and the livable future they are fighting for every day. But more than his campaign work, more than Boston sports — both of which he enjoyed discussing immensely — John loved to talk about his family and how they made everything possible for him. My heart and deepest gratitude are with his wife Donna, his son Coleman and his wife Becca, and the entire Walsh family. We will miss him forever."

U.S. Rep. Jim McGovern: "John was a brilliant political strategist with a heart of gold. He had an incredible mind for grassroots organizing, but more importantly, he was just a fundamentally nice guy. He always reached out to offer his support in good times and bad, and I was blessed to be on the other end of many of those calls. John always bet on the underdog. He’s one of the key reasons why I was an early endorser of Deval Patrick for Governor. He was ahead of most others on most issues and he knew early on that Deval was the right choice to lead Massachusetts, bringing others along with him while spearheading a history-making campaign."

U.S. Rep. Ayanna Pressley: "When embarking on something others deemed impossible or improbable, John Walsh was the person you wanted by your side. John believed unshakably in the possibility of progress and gave generously of his time, his wisdom, and his joy. He was a titan of Massachusetts politics but, more than that, he was a dear friend, a trusted mentor, and a constant presence for so many of us. John was an organizer in the truest sense of the term. His belief in the power of personal connection was indefatigable, and it drove transformational change not only in Massachusetts, but across the country. The legacy of his kindness, his wit, and his commitment to positive change will live on in the generations of staffers, volunteers, and elected officials who had the good fortune to know John and be inspired by him."

Gov. Maura Healey, on X: "Massachusetts owes John Walsh an enormous debt of gratitude for his lifetime of service. John was one of the truly good people. He was brilliant while staying relentlessly humble, optimistic, inclusive, and empathetic to all. His legacy lives on through the countless people he mentored and who remain engaged in civic life trying to make this state and this country a better place. My thoughts and prayers go to John's family and to all who count him as a friend and mentor."

Lt. Gov. Kim Driscoll, on X: "John Walsh represented the best of what grassroots politics can be - strategic, organized and mission-oriented. With a kind heart and hearty laugh, he was a political force for good. My heart goes out to all who knew and loved him."

Attorney General Andrea Campbell, on X: "John wasn’t just kind, smart, and full of hope — he was deeply principled and spent his career empowering those around him to do good. I along with so many will miss him dearly. My prayers are with Donna and Coleman. Rest in peace and power, my friend."

Auditor Diana DiZoglio, on X: "Really saddened by the passing of John Walsh, and send love to his family. John saw the positive and powerful potential that government can have when it comes to changing lives. And he acted on that potential with passionate devotion to service in his work. Rest in peace."

Former Patrick spokesman Alex Goldstein, who worked for Walsh on the Patrick campaign and at the state party, on X: "Heartbroken over the passing of my dear friend and mentor John Walsh. There are no words to describe the enormity of his loss to generations of leaders and activists that were transformed by the gifts of his kindness and wisdom. I will miss him so much.

Rep. Mike Connolly, on X: "Rest in peace John Walsh, and thank you for everything you’ve done to elect progressives and to build the capacity of emerging leaders across Massachusetts. We first met in 2012 in the funniest way. I was running for State Rep. as an independent candidate, and I had just snuck out of work to be a guest on WBUR to talk about my campaign. It was my first time in a radio studio and I was definitely nervous. While in the lobby waiting to go on, this guy sitting across from me starts asking all these questions about the race, about the district and our grassroots campaign, and about the response we were getting from voters, etc. I didn’t know who this person was, but by the nature of his questions, it was becoming clear this was someone who really understood campaigns and politics — so finally, I’m like, “excuse me, who are you?” He’s like, “Oh, I’m John Walsh, chairman of the Massachusetts Democratic Party.” He explained he was called in to speak for the incumbent Democrat. I was surprised because I hadn’t realized there would be other guests for this segment. When we went on the air a few minutes later, he graciously complemented me on my efforts and invited me to rejoin the Democratic Party and run for the seat again someday. I didn’t win that 2012 race — but I took John up on his offer — and four years later when I ran for the seat again, he supported me and we won. Thank you John for the words of encouragement and for the support you offered to me and so many others."

Democratic strategist David Axelrod, on X: "Such sad news. John Walsh was the pied piper behind the grassroots campaign that elected @DevalPatrick governor of MA. A big man with a huge heart, John inspired a new generation of leaders and organizers with his idealism, wisdom and humanity."

Gabriel Gomez, former Republican candidate for U.S. Senate, on X: "Very sad to hear about the passing of #JohnWalsh - was fortunate to have become friends with him. He was a larger than life person and will be missed enormously. Absolute giant!"

Former Patrick administration speechwriter Dave Cavell, on X: "Truly F cancer. John Walsh was the most brilliant organizer and strategist I have ever met. And yet he was an even better person. He mentored a generation of young people & changed our state and nation’s politics. May his memory be a blessing.

Doug Rubin, who was part of Patrick's stunning 2006 victory along with Walsh, on X: "John Walsh was probably the most influential person in my professional life. And I'm not the only one who feels that way. His passion, optimism, and never-ending belief in people made the world a better place. He will be deeply missed. Love you, my friend. #CaptainSunshine"

Former Patrick spokeswoman Jesse Mermell, on X: "I met John Walsh 20+ years ago. I was doing youth organizing. He was running Plymouth County Dems. We planned a youth outreach event together & became fast friends. The first of many joint endeavors. Nobody was smarter. Nobody was more humble."