Alexandria Ocasio-Cortez

What might have felt like a pep rally for the Democratic Socialists of America — a meeting of the group’s national political committee to discuss the 2028 presidential election — turned instead into a bruising, acrimonious afternoon.

Some 320 members of the organization had gathered on Zoom on Sunday to decide on a process for a presidential endorsement. Members were fresh off a set of head-spinning victories for D.S.A.-backed candidates in New York, including in two House primaries and a handful of state legislative races. But the meeting, even by the standards of an organization known for infighting, was rancorous, according to several people who were on the call and spoke on the condition of anonymity to provide candid accounts.

Any hope of determining an immediate timeline for endorsing a candidate — most likely Representative Alexandria Ocasio-Cortez of New York, the highest-profile contender associated with the D.S.A. — fell by the wayside, they said. The idea of doing a nationwide nonbinding poll to gauge support was voted on and defeated.

The conflict illustrated the growing pains that D.S.A. chapters across the country, and particularly in New York, are experiencing as they swell in both numbers and influence and seek to translate their newfound heft into more electoral and policy wins. Leading the charge to back Ms. Ocasio-Cortez were some leaders of New York City’s D.S.A. chapter, which some members see as more focused than its national counterparts on political maneuvering as opposed to ideological purity.