For a politician as savvy as Boston Mayor Michelle Wu, it was a surprising blunder.

On a crowded Boylston Street in Back Bay Saturday evening, a man brandishing a knife reportedly tried to stab two people. His targeted victims fled, running for protection into a busy Chick-fil-A restaurant. There, an off-duty police officer quickly sized up the situation, identified himself, and ordered the knifeman to drop his weapon. The alleged attacker, 32-year-old Lemark Jaramillo of Roslindale, refused to back down. The officer fired, killing Jaramillo but potentially saving the lives of numerous innocent bystanders.

Then, at a hastily assembled press conference following the shooting, Wu made an unforced error.

“My condolences and all of our thoughts,” she said as the cameras rolled, “are with the family of the individual whose life has been lost.” She used her opening words not to praise the quick-thinking cop who likely prevented one or more homicides, not to reassure the public that Boylston Street was safe, not to express compassion for the two people who were nearly stabbed — not even to announce that, as with all police killings, an investigation was immediately being opened.

No: Wu’s first instinct was to offer condolences for the knife-wielding aggressor who had been killed before he could commit homicide. The same sentiment was expressed by the two other top officials on the scene, Suffolk County District Attorney Kevin Hayden and Police Commissioner Michael Cox.

As a matter of simple empathy, it is natural to offer words of comfort to the loved ones of someone who has died suddenly and terribly. Whatever wrongdoing Jaramillo may have been involved in, there is no reason to be unkind to his family as they cope with the weekend’s terrible events. But at the scene of what could have been a bloodbath, sorrow for the death of a man who was apparently intent on stabbing unarmed people should not have been the first thing out of the mayor’s mouth. Taking an extra moment to consider before she spoke might have spared Wu a political embarrassment whose timing couldn’t be worse.

Even before the shooting, Wu was scheduled to appear Wednesday at a high-stakes hearing on Capitol Hill. She has been summoned, along with the mayors of New York, Chicago, and Denver, to testify Wednesday before the US House Oversight Committee about the city’s so-called sanctuary policy and its impact on public safety. The committee’s Republican majority has been touting the hearing as a showdown that will link the Democratic mayors to dangerous crimes committed by immigrants without legal status. An absurdly over-the-top video released by the committee opens with President Trump accusing “radical and corrupt” officials of providing “sanctuary and protection for dangerous criminals” — and ends with a threat by Chairman James Comer, a Kentucky Republican, to “cut as much of their federal funding as we can cut.”

In reality, Boston is not notorious for harboring criminal offenders; it is arguably the safest big city in America. But serious crime certainly occurs in Boston, and the last thing Wu needed this week was a high-profile incident focusing attention on violence in the Back Bay. When she began her press conference by offering condolences for the armed-and-dangerous offender who was shot by a quick-thinking police officer, critics quickly noticed. Her remarks drew scathing attention on social media. She was mocked by, among others, Representative Nancy Mace, a South Carolina Republican who sits on the Oversight Committee, and Trump’s new attorney general, Pam Bondi, who posted: “This DOJ will NEVER apologize for taking down dangerous criminals and getting them off our streets. Thank you to the brave law enforcement officer in Boston who stepped up to protect those in need.”

I doubt that Wu intended to suggest she cares more about criminals than about victims. But it isn’t hard to understand how such a subtext could be inferred. Expressing sympathy is a natural human response, but the wrong context and timing can transform a moment of compassion into a political liability. Wu’s words reinforced that Democrats and progressives have a longstanding problem when it comes to law and order — and Republicans and conservatives are by no means the only voters who say so. To be fair, Wu has opposed her party’s extremists when it comes to crime, vetoing defund-the-police budget cuts passed by City Council. Just this week she was endorsed for reelection by Boston’s largest police union.

But the mayor’s miscalculation on Boylston Street is a reminder that in our unforgiving political climate, every utterance can ignite partisan flames. Now, her impending congressional appearance becomes even more daunting. With critics poised to seize on every nuance, she faces the double challenge of defending both her policies and her lapse in judgment.