The Rent Guidelines Board approved at least 3 percent increases for New York City’s one million rent-stabilized apartments, rejecting the call for a rent freeze that helped Assemblyman Zohran Mamdani surge to the lead in the Democratic mayoral primary last week.

Mayor Eric Adams, who appointed the members of the board, has supported rent increases for rent-stabilized apartments every year since he took office. Mr. Mamdani, likely to be the Democratic nominee facing him in the general election in November, has promised not to do the same if he becomes mayor.

As the city faces linked affordability and housing crises, the contrast between Mr. Mamdani and Mr. Adams added a new layer of tension to the board’s decision.

On Monday night, the board, in a 5-to-4 vote, approved 3 percent increases for one-year leases and 4.5 percent increases for two-year leases.

The board took preliminary votes this spring to back increases of between 1.75 and 4.75 percent on one-year leases, and between 3.75 and 7.75 percent for two-year leases. Any increases would apply to leases beginning in or after October. Mr. Adams had said that the higher range was too high.

As in past years, the discourse around the vote reflects the rift between pro-renter and pro-landlord political interests in New York City. But it is also providing an opportunity for Mr. Mamdani and Mr. Adams to distinguish themselves from each other at a time when making the city a more affordable place to live is a key issue driving the election.