India Walton Beat the Buffalo Mayor in a Primary. He Won’t Give Up.

On paper that would seem like a fait accompli: Ms. Walton is the only person on the ballot.

But Mr. Brown, a lifelong Democrat who is the city’s first Black mayor, seems to be banking on a coalition of business leaders and conservatives, some labor groups and loyal voters who approve of his 16 years in office to vault him to victory.

Long known as a mild-mannered moderate, Mr. Brown has hardened his rhetoric in response to the threat of political oblivion, portraying Ms. Walton, a registered nurse making her first run for public office, as an inexperienced interloper.

“I am convinced that she is unqualified for this position,” said Mr. Brown, 63, in a recent interview. “And if she became mayor of the city of Buffalo, it would be a disaster for this community.”

Nor does he see any problem with accepting the support of Republicans.

“The way I look at it, an election isn’t over until the general election has been held,” Mr. Brown said. “So I see no concerns with optics at all.”

Such statements are galling to Ms. Walton, 39, who says the mayor’s intransigence is doing a disservice to the residents of the very city he says he loves.

“I believe that if the mayor wants what’s best for Buffalo, he would have conceded, he would have helped with a productive transition, and gracefully bowed out,” said Ms. Walton, sitting in her single-room downtown campaign office. “But instead he’s throwing a tantrum.”

Mr. Brown’s ongoing campaign has made some Democrats queasy, as well as put elected officials in an awkward political position. Among them are Ms. Hochul, a Buffalo native, who is faced with either abandoning Mr. Brown — a former head of the New York Democratic state party — or risking alienating the ascendant left wing.