Amazon warehouse workers on Staten Island have enough support for a union election, federal officials have ruled. That could mean the second unionization vote for Amazon this year.

The National Labor Relations Board says it has found "sufficient showing of interest" among Amazon workers at a Staten Island warehouse to set up a vote. The board's ruling on Wednesday comes days before Alabama warehouse workers begin their revote on whether to join a union.

At stake is whether Amazon might get its first unionized warehouse in the United States. The company has grown into the country's second-largest private employer with almost 1 million U.S. workers as of last year.

Last spring, warehouse workers in Bessemer, Ala., held the first Amazon union vote in the U.S. in years but overwhelmingly voted against unionizing. Later, the NLRB ruled Amazon's anti-union campaign tainted that election enough to scrap the results and set a revote. That new election begins next week with almost 6,200 warehouse workers eligible to vote. Results are expected in late March.

The Staten Island labor push stands out for being unaffiliated with any national union. It's a product of a self-organized, grassroots worker group called the Amazon Labor Union, financed via GoFundMe. It is run by Chris Smalls, who led a walkout at the start of the pandemic to protest working conditions and was fired the same day.

The group estimates that more than 5,000 workers might vote on whether to form a union at the Staten Island warehouse. Smalls told NPR over 2,500 workers signed cards in favor of a union election. Employees there pack and ship products for the massive New York market; organizers say they want longer breaks, better medical and other leave options and higher wages.

"The momentum is with us, the energy is with us, the workers are excited," Smalls said on Wednesday. "We're celebrating at this moment but we know it's going to be a long hard battle ahead. We're prepared."

A unionization petition typically requires at least 30% of the workers to sign paperwork saying they want a union. Amazon spokesperson Kelly Nantel said on Wednesday the company was "skeptical that organizers had a sufficient number of legitimate signatures and we're seeking to understand how these signatures were verified."

"Our employees have always had a choice of whether or not to join a union, and as we saw just a few months ago, the vast majority of our team in Staten Island did not support the ALU," Nantel said, referring to the Amazon Labor Union.

In November, local organizers withdrew their original petition for a union vote but refiled it in December. Smalls said on Wednesday that the votes have been verified by the NLRB against payroll.

Amazon, the labor organizers and the NLRB will have to sort out procedural issues, including the size of the potential bargaining unit, before a vote can be scheduled. A hearing is expected on Feb. 16.

Editor's note: Amazon is among NPR's recent financial supporters.