Mayor Setti Warren’s decision to not seek a third term has launched beginning of what’s certain to be a hotly-contested municipal election season in Newton.

So far, two veteran City Councilors — Scott Lennon and Ruthanne Fuller — have said they would like to succeed Warren, with other candidates expected to emerge.

In addition to electing a new mayor next November, voters will be asked to ratify a new charter that could, among other things, shrink the size of Newton’s City Council from 24 to 12 and possibly introduce term limits for city council and/or mayor.

Every seat on the council and school committee will be also up for reelection next fall, including seats Lennon and Fuller will vacate as they run for mayor. And two of the eight school committee members will also be leaving due to term limits.

Warren came into office as a political outsider in 2010, defeating State Rep. Ruth Balser in a closely contested contest. His current term expires at the end of 2017.

“When I ran for mayor in 2009, I pledged to address the city’s financial crisis, maintain the excellence of the school system, set Newton on track for long-term financial health, repair the city’s crumbling roads and public buildings, and bring honesty, openness, and accountability to city government,” Warren said. “I’m so proud that together, we have accomplished these goals and so much more.

Chamber President Greg Reibman said Newton’s businesses and non-profits enjoyed a good working relationship with Warren and his administration.

“The chamber is grateful to Mayor Warren for his consistent support of the business community and Newton's economic and cultural vitality. We appreciate the sound fiscal management practices he brought to City Hall and his efforts to revitalize our village centers, business districts, streets, sidewalks and schools. He deserves credit for having the original vision for the N-Squared Innovation District and for bringing Mass Challenge to Newton.”

U.S. Congressman Joseph Kennedy described Warren as “a public servant in the truest definition of the term.”

“Newton has been lucky to have him in City Hall for the past [seven] years,” Kennedy said in a statement. “I am honored to have had the privilege of working closely with him and wish him and his family the very best in their next chapter.”

Warren, 46, is widely believed to be considering running for governor in 2018. He has hired John Walsh, the former state Democratic Party Chairman who helped run Deval Patrick’s first gubernatorial campaign, as an advisor and is attending fundraising events.

“I am making this announcement now to give our community an adequate amount of time to select the next mayor, and I look forward to the coming year as I continue to serve the city through the end of my term,” Warren said in a statement issued in early November.

City Councilors Lennon and Fuller were the first to announce their candidacies but they won’t likely be the last. Ward 8 Councilor at-large Rick Lipof has said he is considering a run and there’s been speculation about others.

Lennon, a Nonantum native, was first elected in 2016 and has been council’s president for the past seven years. He works professionally as an auditor in the Middlesex Sheriff’s Office.

“I believe my in-depth familiarity with city government, plus my professional financial expertise and managerial skills will contribute to both maximizing the city’s revenue and improving the quality of life for all Newton residents,” Lennon wrote in a statement to the chamber.

“My priorities for the business community would be to publicly promote the strong interrelationship between Newton’s business community and the welfare of its citizens, to ensure businesses have a strong working relationship with City Hall, and most importantly, to recognize them as partners in civic decisions that affect them so as to ensure their growth and prosperity,” he added.

Fuller, a Chestnut Hill resident who is originally from Detroit, has served on the council since 2010. She is currently vice chair of the Finance Committee and has worked developing strategic plans for companies and nonprofits.

“I’m running for mayor to accelerate Newton’s progress in education, housing, infrastructure and management, where I have engaged deeply on policy and finance for the last decade,” Fuller wrote in an email. “I am committed to running a positive campaign and a grassroots campaign where I listen carefully to people's views about Newton's future.

“I look forward to working with the chamber to promote both the growing innovation economy and a business-friendly environment to attract and retain a diverse mix of businesses that can start here, grow here and stay here,” Fuller added.

Reibman said businesses and commercial property owners will be anxious to learn more about the candidates’ platforms as it relates to economic development, traffic, transportation, business regulations, addressing the city’s workforce housing shortage and nurturing the innovation economy.

“Mayor Warren laid the groundwork on a number of initiatives, especially in his second term, which I feel is leading Newton in the right direction,” Reibman said. “But we also know that there is much that could be done to improve the business climate here. We’ll be listening closely and carefully to all the candidates to understand their visions for Newton.”