Outside political groups, also known as super PACs, played a big role in the 2021 mayoral race, spending millions to boost their chosen candidates while knocking rivals in mailers and on TV.

This year’s off-year municipal election, with low turnout expected, has drawn at least one such group that hopes to make a mark in the four-way preliminary for District 5. The group, calling itself “Enough is Enough,” aims to oust incumbent Councillor Ricardo Arroyo, who has held the Hyde Park and Mattapan seat since January 2020.

Arroyo is on the Sept. 12 preliminary ballot with three challengers: Enrique Pepen, who has held a Wu administration post and served as an aide to Congressman Joe Kennedy III; Jose Ruiz, a longtime Boston Police officer; and Jean-Claude Sanon, who has previously run for the seat. Two winners will advance to the November final election.

In a filing with the state Office of Campaign and Political Finance, the “Enough is Enough” super PAC laid out its purpose: “Oppose the election of Ricardo Arroyo and to support the election of his opponents.” Gemma Martin, who runs a campaign finance compliance firm based in Dedham, is listed as the chair and treasurer.

The super PAC’s exact course of action is unclear, as its fundraising and expenditures haven’t been filed yet. But if it follows outside groups in previous elections, direct mail sent to voters’ doorsteps is a likely action, targeting Arroyo.

Arroyo has offered up plenty of ammunition for any opponents: In June, he agreed to pay a $3,000 fine for violating state conflict of interest laws, after admitting that while a councillor he served as a lawyer for his brother Felix in a lawsuit involving the city of Boston. That agreement came roughly a month after his name appeared all over two federal investigatory reports into former US Attorney Rachael Rollins, who was accused of attempting to tamper with the 2022 race to replace her as district attorney.

In August 2022 as the DA race was raging, the state Ethics Commission’s enforcement division contacted him about representing his brother. At the same time, Arroyo was messaging with Rollins, asking if her office was announcing an investigation into the interim DA at the time, Kevin Hayden. “Would be the best thing” Arroyo said, and noted Boston Globe reporters were questioning him about sexual assault allegations from his high school years. Arroyo has noted he was never charged and he denied any wrongdoing in the Rollins matter.

On Tuesday, the Boston Herald reported that an attorney who works for the 13-member City Council filed an internal complaint against three councillors, including Arroyo. She said she had been bullied and harassed by the trio. Arroyo told the newspaper the allegations were “baseless.”

In a statement, Arroyo campaign manager Patrick Keaney said they are focused on "running a clean campaign focused on the issues and Ricardo’s record of accomplishments for the residents of District 5."

He added: "We are confident voters will reject dirty and negative campaigning funded by the dark money behind this Super PAC. His opponents should also reject this PAC's efforts and commit to a positive campaign, focused on the issues, which is what the residents of District 5 want and deserve.“

According to fundraising totals for July, Ruiz outraised Arroyo, bringing in just over $20,000 to Arroyo’s $16,467. Arroyo had $27,270 in cash on hand at the end of the month, while Ruiz had $25,298. Pepen raised $7,872 and Sanon reported just under $4,000.

Meanwhile, first-time candidate Pepen has pulled in several labor endorsements, including Dorchester-based IBEW Local 103, Bricklayers Local 3, and UNITE HERE Local 26.