Why is Rachael Rollins picking a fight with Marty Walsh?

If you’re sitting in the Oval Office, does her commentary come across as courageous or injudicious?

Suffolk County District Attorney Rachael Rollins speaks with the media in May outside Dorchester Municipal Court.Pat Greenhouse/Globe Staff

You can say this much for Suffolk District Attorney Rachael Rollins: She’s not afraid to challenge power, even with a nomination on the line to become the next US attorney for Massachusetts.

To make that happen, she needs President Biden’s backing. But that didn’t stop her from offering up a scathing critique of Marty Walsh, the US labor secretary and former Boston mayor with close Biden ties. On WCVB-TV Sunday, Rollins was asked about Walsh’s decision to hire now ex-police commissioner Dennis White, and the ex-mayor’s insistence he knew nothing about past allegations of domestic abuse against White. Her reply: “either [Walsh] knew about it and he’s lying, or he didn’t know about it, and you’re a terrible manager.”

If you’re sitting in the Oval Office, does such commentary come across as courageous or injudicious? Add Rollins’s trademark bluntness to what supporters embrace as a welcome progressive agenda — but opponents see as soft-on-crime — and it’s also interesting to ponder how her nomination might play out in a highly polarized Senate, which must confirm her. Given all that, Rollins almost seems to be daring Biden not to choose her.

Rollins, the first woman of color to win election to the Suffolk DA’s job, is the local face of a national movement that promotes rehabilitation over incarceration and demands more police accountability. Today, that progressive criminal justice agenda, like all progressive agendas, is under attack from the right. If she’s Biden’s pick, it’s easy to see the law and order crowd ramping up attacks against her.

On the one hand, she’s not backing down. Consider the back and forth between Rollins and Bill Bratton, a former Boston police commissioner who also led the New York and Los Angeles police departments. Bratton, the author of a new book, “The Profession,” told the Boston Herald that Rollins is “well-intended” but has “lost sight of the fact very bad, very vicious people deserve to be in jail.”

In response, Rollins said her agenda is to prioritize violent crimes and remove the most violent perpetrators from the community. She then went on to blast Bratton’s tenure in Boston, noting that the Boston Police Department was under a federal consent decree at the time, because the department “refused to diversify its police force to reflect the community it serves, so it had to be sued and legally forced to do so.” And she also called out Bratton for the arrest of Sean Ellis in the murder of a police detective, a case that happened on Bratton’s watch, and what she said “arguably involved the most corrupt and egregiously unconstitutional investigations” the department has seen. A judge recently ruled that Ellis, who spent 22 years in jail, is entitled to a new trial, but Rollins has said she will drop the charges.

I like politicians who don’t sugarcoat their feelings, but Rollins can take it too far. When a local TV news crew tried to follow up on an alleged road rage incident that happened on Christmas Eve, and approached her at her home, Rollins threatened to call police and have the news person arrested. An investigation by Attorney General Maura Healey cleared Rollins of any wrongdoing involving the parking lot encounter, but the incident still shapes public perception of who she is.

To Rollins’s credit, she makes people think hard about the meaning of justice and the best way to fight crime. Yet there’s still a line of decorum that prosecutors traditionally walk. The job requires someone who looks as if they’re making decisions on the facts and the law, not on the basis of a personal agenda.

With the White debacle, Walsh faces legitimate questions. But when the allegations of domestic abuse first came to light, and Walsh put White on administrative leave, the National Organization of Black Law Enforcement Executives of Massachusetts — whose executive board includes Rollins — backed White’s reinstatement. After an independent investigation, Acting Mayor Kim Janey fired White. As part of the campaign to fight White’s termination, former BPD Commissioner William Gross submitted an affidavit which suggested Walsh was briefed on the allegations against White. Because of that, Rollins has said Gross is “more credible” than Walsh.

Sticking with Gross also gives Rollins some welcome standing with police — which would boost her nomination, given her less popular calls for police accountability. And that may be what this fight with Walsh is really about.