The members of the biggest labor union at the city’s embattled New York City Housing Authority rejected a tentative contract deal that traded bonuses and wage hikes in exchange for weekend shifts.

NYCHA workers who are Teamsters Local 237 nixed the much-heralded deal by 3-2 margin, according to a tally seen by The Post.

“They rejected the city’s offer,” said Teamsters 237 president Greg Floyd in a statement. “And now this will go to arbitration.”

Union members cast 357 votes against the deal, while 210 members backed it. Another four ballots were challenged.

All told, fewer than half of the 1,277 votes mailed out were returned.

“This Administration’s goal remains the same: reach a contract agreement that meets the needs of NYCHA residents and that is fair to maintenance workers and New York City taxpayers,” said City Hall spokesman Raul Contreras. “We’re in conversations with union leadership to determine next steps in order to achieve this goal.”