Elizabeth Warren endorses Wu in Boston mayoral race, calling the candidate ‘a fighter’

Michelle Wu kicked off her campaign for Boston mayor on Sept. 15.Jim Davis/Globe Staff

US Senator Elizabeth Warren endorsed Boston City Councilor At Large Michelle Wu Saturday in the race to succeed Mayor Martin J. Walsh, calling her a “fighter.”

“Michelle has always been a fighter — as one of my students, as a Boston city councilor, and now as a candidate for Mayor,” Warren said in a statement Saturday.

President-elect Joseph R. Biden picked Walsh as his choice for labor secretary, and the mayor’s departure leaves the race open for only the second time in nearly 30 years.

“She is a tireless advocate for families and communities who feel unseen and unheard,” Warren said in her endorsement.

“Bostonians can count on Michelle’s bold, progressive leadership to tackle our biggest challenges, such as recovering from the pandemic, dismantling systemic racism, prioritizing housing justice, revitalizing our transportation infrastructure, and addressing the climate crisis,” Warren said.

The endorsement from Warren, who holds influence over progressives in Boston, is a timely win for Wu, though not entirely unexpected. Wu has longstanding ties to Warren, first as a student at Harvard Law, and later as a campaign aide and statewide constituency director for her Senate campaign. The two have previously campaigned for each other.

“Elizabeth Warren has been a friend and a mentor for a long time and a thought partner in delivering change for Boston residents and families across the Commonwealth,” Wu said in an interview.

Though Wu already had ties to Warren’s team, the senator’s endorsement could encourage her political advisers and financial supporters to align with Wu in the hotly contested sprint to become the next mayor of Boston.

Wu, who became the city’s first Asian-American woman elected to the council in 2013 and the first woman of color to serve as president three years later, has long been viewed as a likely candidate for mayor.

But her September campaign launch was swiftly challenged by Andrea Campbell, the district city councilor from Mattapan since 2015, who succeeded Wu as council president in her second term.

Like Wu, Campbell is a progressive who plans to make equity a theme of her campaign. But Campbell, who is Black, is also seizing on her biography amid the current national reckoning on race.

Within 24 hours of the announcement of the mayor’s exit, she released a campaign video highlighting her deep identification with issues of inequity. A Boston Latin School success story who became an attorney, Campbell was a foster child whose father was incarcerated. Her twin brother died in jail.

“Two lives, two paths, two Bostons — one story of how our city supports or fails us,” she says in the video. “Boston has long been a city divided, where systems that fail some people eventually fail everyone.”

But Wu’s campaign — and Warren’s endorsement — makes clear that she has no intention of ceding any ground. Wu also has a compelling life story. At 23, she became the primary caregiver for her two younger sisters and her immigrant mother, who grappled with mental illness.

“Over the past 7 years, Michelle has carried her life experiences to City Hall as a tireless advocate for women, working families, and communities who feel unseen and unheard,” Warren said in her endorsement.

Warren also said that “Bostonians can count on Michelle’s bold, progressive leadership to tackle our biggest challenges, such as recovering from the pandemic, dismantling systemic racism, prioritizing housing justice, revitalizing our transportation infrastructure, and addressing the climate crisis.”

In an interview, Wu added that she entered the race “because this moment is critical for the city of Boston.”

“We have everything we need to deliver the transformational change that our families deserve” she said. “Boston has the resources, we have the activism, we have the ideas. We need bold, urgent leadership.”

The competition between the two mayoral candidates could be further complicated by Walsh’s exit, which throws open the mayor’s race to newcomers who might not have taken on a popular incumbent.

It will likely also elevate the current City Council president, Kim Janey, to acting mayor, giving her a prime political perch to mount a campaign of her own. The city’s longest-ever serving mayor, the late Thomas M. Menino, first won office after being catapulted into the acting position from the council presidency in 1993.

Janey told the Globe Saturday she is not ruling out a campaign. However, she said in a statement, “My focus right now is working with the Walsh administration on a smooth transition and leading the City in the coming months.”

The race could also be joined by at least a half-dozen other candidates who are said to be considering mounting campaigns. They include Councilor at Large Annissa Essaibi-George; Suffolk Sheriff Steven W. Tompkins; city Health and Human Services chief Marty Martinez; and Democratic state legislators who represent Boston — Representative Aaron Michlewitz of the North End, Representative Jon Santiago of the South End, and Senator Nick Collins of South Boston.

Globe correspondent Lucas Phillips contributed to this report.