Updated at 5:36 p.m. July 10

State Rep. Mike Connolly, D-Cambridge, announced Monday that he's leaving the Boston chapter of the Democratic Socialists of America after the group moved to expel him for, among other things, endorsing Maura Healey in the 2022 Democratic gubernatorial primary and twice supporting Ron Mariano for speaker of the Massachusetts House of Representatives.

Connolly, who had initially vowed to fight the proposed expulsion, told GBH News Monday that his thinking shifted over the course of several days.

"It really became clear that the fundamental charge was that I was building partnerships and working with other state leaders and activists to deliver results for our communities," Connolly added. "I don't think building broad coalitions in support of our goals is an abandonment of our values. I think it's actually necessary for delivering for people in need."

By way of example, Connolly cited his recent push to reverse the planned closure of the MBTA's Union Square station for several weeks this summer. The Healey Administration backtracked on that plan less than a week after it was announced.

In 2022, Connolly's endorsement of Healey came about three weeks before then state Sen. Sonia Chang-Díaz, who was challenging Healey from the left, ended her campaign.

Mariano, who has twice been elected House speaker, has shown both centrist and progressive tendencies in that role. In the most recent legislative session, for example, he backed a business-friendly tax cut plan, while also championing a new law that lets undocumented immigrants obtain driver's licenses.

As it moved to expel Connolly, Boston DSA also cited Connolly's collaboration with sympathetic landlords as he advocates for rent control on Beacon Hill. The Democratic Socialists of America website describes capitalism as a fundamentally exploitative system, and endorses collective ownership of "key economic drivers" like transportation and energy production.

"What was so clarifying for me over the past week was how many people ... reached out and said, 'We love what you're doing and we hope you continue to do it,'" Connolly said. "So it reached a point where, for me, I felt what was most important was to focus on doing the work with good-faith partners."

Connolly, who took office in 2017, is widely regarded as one of the most left-leaning legislators on Beacon Hill. After the 2021-2022 legislative session concluded, he was one of three state representatives honored by the group Progressive Mass, which gave him an A+ for his voting record.

His break with Boston DSA means that just one other state legislator, state Rep. Erika Uyterhoeven, D-Somerville, is affiliated with the group.

On Monday afternoon, the Boston DSA's coordinating committee released a statement saying there would no longer be a vote on Connolly's proposed expulsion, and stressing that the committee as a whole had not endorsed his removal before he announced his exit.

This story was updated to include the Boston DSA's statement.