IN A MAJOR blow to City Councilor Ricardo Arroyo’s already hobbled reelection bid, Mayor Michelle Wu is throwing her support behind one of his challengers, Enrique Pepén, a former City Hall aide, in the race for the district seat representing Hyde Park, Roslindale, a section of Mattapan. 

“Enrique is exactly the kind of leader we need in government,” Wu said in a statement released Monday morning. “He’s thoughtful and kind, creative and tenacious—and above all dedicated to serving the community,” she said of Pepén, the son of immigrants from the Dominican Republic. 

The endorsement is a big setback for Arroyo, who had Wu’s support in his original 2019 run for the seat, but is seen as vulnerable after being engulfed by a string of controversies. 

Wu initially backed Arroyo in his Democratic primary run for district attorney last year, but then pulled her endorsement when years-old allegations of sexual assault surfaced during the race. Arroyo denies the allegations and was never charged in the cases. Despite rescinding her endorsement, Wu said she nevertheless voted for Arroyo, a fellow progressive, in his losing race against Suffolk District Attorney Kevin Hayden. 

Months later, Arroyo found himself again embroiled in controversy, as two federal oversight reports found then-US Attorney Rachael Rollins had improperly worked to aid his DA’s campaign. Arroyo has insisted he did nothing wrong – though Rollins’s violation of rules banning federal employees from involvement in campaigns forced her from office. 

Meanwhile, in June, Arroyo admitted to state ethics violation and paid a $3,000 fine for representing his brother in a lawsuit involving the city while also serving on the council. 

The endorsement could be a significant help to Pepén, one of three challenges vying against Arroyo in the September 12 preliminary election. Also in the race are Jose Ruiz, a retired Boston police officer, and Jean-Claude Sanon, who has run for council unsuccessfully four times. 

“I am profoundly humbled and honored to receive the support of my mentor and friend Mayor Michelle Wu,” he said in a statement. “I share Mayor Wu’s dedication to serve our community and meet people where they are,” said Pepén, who until recently ran Wu’s neighborhood services office. 

He has faced his own controversies, apologizing last month for possible campaign finance violations related to fundraising while working as a municipal employee. Pepén also apparently conducted an interview about his campaign from City Hall, also likely a violation of state law. 

The endorsement will be a test of Wu’s political might. Boston mayors, with strong statutory powers over city government and a huge municipal workforce operating under them, have long been regarded as potent forces in the electoral arena. But they have a decidedly mixed record when it comes to successfully throwing that weight behind other candidates.

In 2019, then-Mayor Marty Walsh backed two candidates in the at-large race for four council seats — incumbent Annissa Essaibi George and challenger Alejandra St. Guillen. Essaibi George prevailed, but St. Guillen was edged out by 1 vote for fourth place by fellow challenger Julia Mejia.

In a well-known example of the limits of mayoral muscle, more than 40 years ago, in 1981, then-Mayor Kevin White endorsed a slate of seven candidates in the race for what was then an all-at-large council. White’s push for the “Kevin Seven,” as they become known, was a spectacular failure, with only one of candidates, Bruce Bolling, winning a seat.

Wu has shown a willingness to dive into other races from the start. In November 2021, less than three weeks after her landslide mayoral win, she endorsed her former city council colleague Lydia Edwards in a special election for a vacant state Senate based on East Boston. Edwards won a hard-fought race, giving Wu and her administration a solid ally on Beacon Hill.

Wu endorsed Sharon Durkan, a former campaign staffer, in her successful special election run last month for a vacant district council seat in Back Bay and Beacon Hill.

Wu didn’t mention Arroyo in her endorsement of his opponent, but it represents the latest hit to the political standing of the outspoken Hyde Park councilor, who hails from a well-known political family. His father was the first Latino elected to the Boston City Council, and a brother also served on the council. 

“Were I Ricardo Arroyo, given how closely he’s worked with Michelle, I’d be devastated by it,” former city councilor Larry DiCara said of the mayor throwing her support to Pepén. 

Arroyo’s campaign did not immediately respond to a message about the endorsement.