Amazon warehouse staff that work at a fulfillment center outside of Albany, New York have filed a petition for a union election with the National Labor Relations Board (NLRB), the NLRB told The Verge on Tuesday. The employees, who work at Amazon’s ALB1 warehouse, have filed for a unit that would encompass around 400 workers at the facility.

To file for a union petition, more than 30 percent of the proposed unit would have signed union authorization cards. The NLRB is currently ensuring that this step has been taken and expects to verify the petition in a matter of days and proceed to arranging a formal election.

The Albany workers are organized with the Amazon Labor Union (ALU), which successfully voted to unionize at the company’s JFK8 warehouse in Staten Island in April but lost a union vote at Amazon’s LDJ5 facility in Staten Island in May. Amazon warehouse workers in Bessemer, Alabama have organized with the Retail, Wholesale and Department Store Union (RWDSU), but their union vote that took place in March was too close to call.

The company has been resistant to union efforts from its warehouse workers, with CEO Andy Jassy telling employees in an all-hands meeting that unions are “much slower and much more bureaucratic.”

“Our employees have the choice of whether or not to join a union,” Amazon spokesperson Paul Flaningan said in a statement to The Verge. “They always have. As a company, we don’t think unions are the best answer for our employees. Our focus remains on working directly with our team to continue making Amazon a great place to work.”

Update August 16th, 6:55PM ET: Added statement from Amazon.