A finalist for U.S. attorney in Boston is publicly trashing the city's former mayor — Labor Secretary Marty Walsh.

Why it matters: Rachael Rollins’ approach is perpetuating scrutiny of a troubled Cabinet secretary and fellow Democrat — and hints at the independence she may exhibit if tapped for top federal prosecutor for the eastern half of Massachusetts.

• It’s also testing the Biden communications shop’s tight-ship, no-drama approach, and would provide fuel for Republican questioning in a prospective Senate confirmation hearing.

Driving the news: Rollins, district attorney of Boston-based Suffolk County, has repeatedly complained about Walsh distancing himself from a scandal that emerged just before he started working in Washington.

• In a last-minute move, the outgoing mayor named Dennis White to be the city's new police commissioner.
• Two days later, Walsh suspended White after The Boston Globe reported he had faced domestic violence allegations from his ex-wife.
• Walsh's replacement, acting mayor Kim Janey, fired White, but he sued to retain his job.
• An independent report and subsequent court proceedings included sworn affidavits stating Walsh knew about White's past before putting him in the new job — something Walsh has denied in statements to the media.

What they're saying: “Somebody signed something under the pains and penalties of perjury. For me that has to trump … somebody just saying, ‘Yeah, that never happened,’” Rollins told "Boston Public Radio" last month.

• "I think our former mayor left a very big mess for our acting mayor," she added.
• Another Democrat, Rep. Seth Moulton (D-Mass.), said Walsh should resign if he knew about the White accusations.

In an interview that aired Sunday, Rollins went further.

• “This is a bad situation overall, because either he knew about it and he’s lying, or he didn’t know about it and you’re a terrible manager, right?” the DA told WCVB-TV’s “On the Record."
• Rollins also confirmed she is one of three finalists for U.S. attorney.

The statements renewed a stir in Boston's political community, in part because Rollins would be teammates with Walsh if she joins the Biden administration.

• Administration nominees tend to remain silent while being vetted.
• Rollins has now engaged in two high-profile interviews, the second coming after the first renewed scrutiny of Walsh.

The White House declined to comment.

• Rollins said Tuesday in a tweet: "This unforced error has cost our City millions & counting. As taxpayers, we foot the bill. It has distracted attention away from the hard work BPD does in our communities every day. Being silent & meek isn’t in my job description. We have murders to solve."