Citi Bike mechanics, station technicians and other employees who run New York City's bicycle-sharing program could vote on whether to join a union as soon as next month following a decision by the National Labor Relations Board on Wednesday.

The board's decision marked a victory for union organizers who had sought to include seasonal workers and many of the program's supervisors as eligible to join a collective bargaining unit, labor experts said.

About 96 of 249 Citi Bike workers are classified as seasonal, according to the NLRB.

"It's a win for the union," said Rebecca Givan, a professor of labor studies at Rutgers University. "You want to have full coverage to prevent the possibility of one group of employees being pitted against each other or being treated differently."

The unionizing effort could further complicate matters for Citi Bike's operator, Alta Bicycle Share Inc. of Portland, Ore., as it hammers out a deal to sell a controlling stake to REQX Ventures, a New York City-based investment firm affiliated with real estate giant Related Cos.