District 3 Councillor Frank Baker’s decision against running for reelection has opened up a seat in a recently reconfigured district that curves down from the Ink Block complex in the South End to Gallivan Boulevard in Dorchester’s Neponset neighborhood and includes more of Fields Corner, which has long been a Vietnamese residential and commercial stronghold.

The field has two declared candidates, a teacher and a community activist, while others are said to be considering a run, including an attorney who worked as US Sen. Elizabeth Warren’s campaign field director in 2012, a former Beacon Hill aide, a Boston Public Schools adviser who managed Marty Walsh’s first mayoral campaign, and a leader in the Cape Verdean community.

Joel Richards, an educator backed by the Boston Teachers Union, and Jennifer Johnson, a community activist, are the two declared candidates, who jumped into the race before Baker ruled out a run for a seventh two-year term.

“I applaud Councillor Baker on his dedicated service to our city and wish him and his family well,” Richards said Thursday. “I got into this race because the people of District 3 deserve a council member who will fight to lower housing costs, improve our schools, and help our small businesses.”

Johnson, the president and a leader of Meetinghouse Hill Civic Association for a decade, said she wished Baker well and noted that she often worked behind the scenes with him. “Now I look forward to putting my years of experience in District 3 to work for my neighbors around the urgent issues facing our city, including housing, public education, and delivering city services equitably,” she said.

Megan Costello, currently working as a senior adviser in the Boston Public Schools, is eyeing a campaign, the Reporter has been told. A longtime Walsh aide, she managed his 2013 mayoral run.

Adams Village’s Pat O’Brien, a US Army veteran and LGBTQ+-member who served as a staffer to former state Sen. Linda Dorcena Forry and current state Sen. Nick Collins, is definitely jumping in, he told the Reporter on Tuesday. O’Brien signed up for nomination papers last week.

Marty Martinez, an Uphams Corner resident who served as Walsh’s chief of health and human services, said he has received several encouraging texts and emails since Baker’s announcement last Thursday. “I’m giving it a consideration, it’s fair to say,” he said.

Savin Hill’s Matt Patton, an attorney and former field director for Sen.Warren, is also said to be considering a run, and Shirley A. Jones, a member of the Ward 15 Democratic Committee, could also be a contender.

Bowdoin Geneva’s Paulo De Barros, director of the Cape Verdean Association of Boston, is also seen as in the mix as a potential candidate.

Ten years after his campaign for the District 3 seat, John O’Toole’s phone has started ringing again. But the longtime civic activist told the Reporter he will likely sit out this race.

He said he made peace with Baker after 2011, noting, “I appreciate the work that Frank did in the district,” O’Toole said.

He’ll be tracking the race closely from the sidelines, though. “The Council’s become a bit chaotic these days,” he said. “I’m hoping someone can bring back some civility and unity.”

News Editor Seth Daniel contributed to this report.