Sitting in the cool of a Williamsburg cafe one recent morning, Antonio Reynoso looked pained as he tried to make sense of how a progressive like him ended up at war with Mayor Zohran Mamdani over a prized New York City House seat.<\/p>\n
Mr. Reynoso, the Brooklyn borough president, has been a loyal ally of the mayor and, in another time, might have expected his support. But when a longtime congresswoman\u2019s surprise retirement<\/a> opened the seat, Mr. Mamdani saw an opportunity, too, and backed a little-known state assemblywoman who would advance his brand of democratic socialism.<\/p>\n There were attempts to deconflict. Mr. Mamdani offered to discuss \u201cother opportunities\u201d for him, Mr. Reynoso said, but the candidate would not budge. Mr. Reynoso, in turn, suggested that Mr. Mamdani reconsider his support for the assemblywoman, Claire Valdez<\/a>.<\/p>\n \u201cHe didn\u2019t want to have that conversation,\u201d Mr. Reynoso recalled. \u201cSo we ended it there.\u201d<\/p>\n Six months later, the disagreement has transformed what could have been a sleepy race for a solidly Democratic seat into a hard-fought primary<\/a> that is driving a wedge through the heart of Mr. Mamdani\u2019s coalition and offering up a preview of a new kind of struggle.<\/p>\n Where most other city races have followed a familiar pattern, pitting a united left against the moderate establishment, the primary in New York\u2019s 7th District has turned the left against the lefter.<\/p>\n And on the ground in the Brooklyn and Queens neighborhoods that make up the district, the contest is stirring up uncomfortable questions about race, class and rapid gentrification that the left rarely wants to acknowledge.<\/p>\n On one side is Mr. Reynoso, 43, the Brooklyn-born son of working-class Dominican immigrants, who has helped build the city\u2019s progressive movement for 15 years. Lined up with him are many of the players who, until very recently, were its arbiters: Black and Latino politicians, major labor unions and the Working Families Party<\/a>.<\/p>\n On the other is Ms. Valdez, 36, a Latina and Native American from Texas who moved to the area alongside other young, college-educated newcomers and concluded that progressives were not thinking boldly enough. She has the backing of Mr. Mamdani and the Democratic Socialists of America, who were emboldened by last year\u2019s mayoral result.<\/p>\n (City Councilwoman Julie Won<\/a> and Vichal Kumar, a public defender, are also running, but have gained less traction.)<\/p>\n \u201cThis is the new battle line in New York City and urban politics,\u201d said Michael Lange, a writer with ties to both factions who coined the term \u201cCommie Corridor\u201d<\/a> to describe the district\u2019s overwhelmingly young and left-leaning electorate.<\/p>\n He added: \u201cThere are going to be plenty of neighborhoods and districts where the past establishment has receded, and the frontier is now socialists versus progressives.\u201d<\/p>\n The policy distinctions in the race can be difficult to discern. Both candidates support abolishing ICE, want to raise taxes on the rich and cite the crushing costs of housing as their top priority.<\/p>\n But the tribal politics are hard to miss.<\/p>\n Representative Nydia Vel\u00e1zquez, the Puerto Rican trailblazer surrendering the seat after spending three decades as a kind of godmother to the city\u2019s left, has openly chafed at Mr. Mamdani\u2019s involvement<\/a> in the race.<\/p>\n \u201cI\u2019m not going to allow D.S.A. to define who is progressive and who is not,\u201d she said recently after campaigning with Mr. Reynoso, her preferred candidate. \u201cBecause the fact that they are here, I paved the way for that.\u201d<\/p>\n Gustavo Gordillo, one of the organization\u2019s top New York leaders, said he agreed with the congresswoman about her influence \u2014 but that the world had changed.<\/p>\n \u201cThere were different approaches to left politics on the ballot last election, and it was the democratic socialist approach that won,\u201d he said.<\/p>\n Polling has been scant, but it suggests a close race. Mr. Reynoso\u2019s name recognition, record and endorsements would historically have given him the upper hand. But both sides agree that Mr. Mamdani\u2019s popularity may be more than enough for Ms. Valdez to overcome her short tenure (she has served in the Assembly since last year).<\/p>\n Mr. Mamdani, for his part, did not comment on Mr. Reynoso\u2019s candidacy but said in a statement that he supported Ms. Valdez because she had the \u201ccourage to do what\u2019s right even when it isn\u2019t easy.\u201d<\/p>\n \u201cWe need to fundamentally change who has power in this country,” he said, \u201cand Claire will spend every day working to do exactly that.\u201d<\/p>\n The contest is playing out against a backdrop of demographic changes that have transformed the area over the last quarter century from an immigrant-heavy enclave into an internationally recognized symbol of gentrification.<\/p>\n The district, which runs from Downtown Brooklyn to Queens, stretching to Astoria in the north and Woodhaven in the east, is still about a third Latino, according to census data, and is home to working- and middle-class neighborhoods and public housing.<\/p>\n Yet in the decades since developers first began putting up luxury apartment towers along the postindustrial waterfronts of Williamsburg and Long Island City, an influx of new residents has driven the average age down and already liberal politics further left.<\/p>\n In last year\u2019s mayoral primary, Mr. Mamdani won 75 percent of the vote there. Today, the district boasts nearly 3,000 dues-paying D.S.A. members, more than elsewhere in the city.<\/p>\n Both leading candidates insist they are campaigning across the demographic divide. But strategies detailed in so-called red boxes on their campaign websites, where candidates give instructions to outside super PACs, suggest distinct bases.<\/p>\n In her instructions<\/a>, Ms. Valdez listed ZIP codes where the groups should spend, starting with Williamsburg, Greenpoint and Ridgewood, areas that are now home to large pools of college-educated white voters. Mr. Reynoso, by contrast, put up instructions<\/a> asking for outside groups to target voters over 35 and all voters of color.<\/p>\n As she campaigns, Ms. Valdez displays few qualms about her identification with the area\u2019s newer residents. She moved to the city in 2015 to pursue a \u201ccareer in the arts,\u201d she said. Instead, she found rising rents and diminishing opportunities, even for those with degrees and cultural capital. <\/p>\n \u201cI don\u2019t think it takes very long to see how hard it is to live in this city,\u201d she said in an interview at a Long Island City diner.<\/p>\n Ms. Valdez does not dispute that Mr. Mamdani\u2019s involvement has galvanized support for her campaign. But she argues that voters want her more ideologically committed politics.<\/p>\n An outspoken critic of Israel\u2019s war in Gaza, Ms. Valdez has criticized Mr. Reynoso for not describing the conflict as a genocide until last year. Where he has advocated reforms within existing systems, she wants to shrink the private sector and drastically ramp up the federal government\u2019s role in building housing.<\/p>\n The district, she said, \u201cis one of the most progressive, if not the most progressive,\u201d in the country.<\/p>\n \u201cThe person who leads it should be someone who\u2019s going to stand up for justice, who\u2019s going to have real moral courage and conviction,\u201d she said. \u201cI didn\u2019t see that from the borough president until he started running for Congress.\u201d<\/p>\n The assemblywoman and her allies have also knocked Mr. Reynoso for accepting tens of thousands of dollars in campaign contributions from people connected to the real estate industry.<\/p>\n \u201cIt is the real estate industry that is most responsible for turning New York City into a playground for the rich,\u201d Mr. Gordillo said. \u201cIt\u2019s the most basic litmus test to show you are behind working people.\u201d<\/p>\n Mr. Reynoso\u2019s campaign pushed back, pointing out that it had taken donations from smaller industry players, not corporate landlords or developers.<\/p>\n Mr. Reynoso is trying to use his experience to try to distinguish himself. He highlights his role as a founder of the New Kings Democrats, which helped uproot the more moderate Brooklyn political machine, and the fact that he personally defeated Vito Lopez, its boss, in a 2013 City Council race.<\/p>\n