Boston City Councilor Ricardo Arroyo announced Tuesday his bid for Suffolk County district attorney.

Arroyo, a former public defender, said he is poised to pick up the progressive prosecutor mantle left when former DA Rachael Rollins was appointed to the Massachusetts U.S. Attorney’s office.

“Former District Attorney Rachael Rollins led the way by bringing much-needed reform to this office. We cannot afford to go backwards or stagnate,” Arroyo, 34, said during a press conference in Roslindale.

“I represented hundreds of individuals and I witnessed daily how inequity, the lack of opportunity and the lack of resources and marginalization of individuals ravaged lives. All of those experiences demonstrated to me a need for a true progressive approach to justice that holds people accountable, yes, but also offers healing and wholeness for survivors and all involved.”

Arroyo, who was recently re-elected to his Boston City Council seat, pointed to his efforts to declare racism a public health crisis, to reallocate public safety money toward mental health and violence prevention, and ban facial recognition technology.

Arroyo told GBH News he does not anticipate struggling to balance his campaign for district attorney with his work representing his district, or negotiating contentious topics like the effort to revive an elected school committee in Boston and the move to bring a reparations commission to the city. A primary will be held in September before a final vote in November.

“The work that I do on the council has always been directed towards making our community stronger and more vibrant. I will continue to do that work. There will be no letup in the work that I do as a councilor while I’m running for DA,” Arroy said.

The Roslindale-Mattapan city councilor is the first to officially declare his candidacy for Suffolk County district attorney.

Gov. Charlie Baker appointed former Sex Offender Registry Board Chair Kevin Hayden to serve out the remaining year of Rollins' term, which expires in 2023.

Hayden, who also lives in Roslindale, filed paperwork for a DA run last month and is expected to officially declare his candidacy soon.

Asked about running against Hayden who has something of an incumbent's advantage, Arroyo said he is only worried about policies changing before an elected DA enters the office.

“I only worry insomuch as these policies have a made a difference in many people’s lives and it is my sincerest hope that because the last elected Suffolk County DA put these policies in place that they not be changed or altered until the next elected Suffolk County District Attorney takes office.”

Arroyo sits on a war chest of about $90,000, according to the latest state campaign finance records. Hayden’s recently opened campaign account contains $1,000.

Arroyo was first elected to the council in 2019 in a race widely viewed as emblematic of Boston's shifting demographics and progressive political tilt. His father, Felix D. Arroyo, is the Suffolk County register of probate and a former Boston city councilor.

At-Large City Councilor Michael Flaherty is also weighing a run for the office, according to sources close to him.

The Suffolk County district attorney manages criminal cases for Boston, Chelsea, Revere and Winthrop.