NEW YORK (AP) — A new union election for Amazon workers in Bessemer, Alabama will be held based on objections to the first vote that took place in April.

The move is a major blow to Amazon, which had spent about a year aggressively campaigning for warehouse workers in Bessemer to reject the union, which they ultimately did by a wide margin.

The rare call for a do-over was first announced Monday by the Retail, Wholesale and Department Store Union, which spearheaded the union organizing movement. A National Labor Relations Board spokeswoman confirmed the decision but did not yet provide details.

The RWDSU charged Amazon with illegal misconduct during the first vote. In August, the hearing officer at NLRB who presided over the case determined that Amazon violated labor law and recommended that the regional director set aside the results and direct another election.

The main reason for the determination was a U.S. Postal Service mailbox Amazon installed in the parking lot ahead of the election, which could have left the false impression that the company was running the election. Security cameras in the parking lot could have scared off workers who thought Amazon may have been watching workers vote. About 53% of the nearly 6,000 workers cast ballots during the first election.

Kelly Nantel, an Amazon spokesperson, called the decision “disappointing.”

“Our employees have always had the choice of whether or not to join a union, and they overwhelmingly chose not to join the RWDSU earlier this year,” she said. “It’s disappointing that the NLRB has now decided that those votes shouldn’t count.”

Stuart Appelbaum, president of the RWDSU, sees the NLRB decision as a victory.

“Today’s decision confirms what we were saying all along – that Amazon’s intimidation and interference prevented workers from having a fair say in whether they wanted a union in their workplace – and as the Regional Director has indicated, that is both unacceptable and illegal, “ he said in a statement. “Amazon workers deserve to have a voice at work, which can only come from a union.”

But even with a second election, labor experts say a union victory is a long shot. Amazon will likely appeal and try to delay another vote. And even when an election is held, workers may chose to vote against joining a union again. Last time around, 1,798 workers rejected the union and 738 voted in favor of it.

A repeat of the election means another battle for Amazon with the RWDSU. The first election garnered nationwide attention and put a spotlight on how Amazon treats its workers. It was the biggest union push in Amazon’s history and only the second time that an organizing effort from within the company had come to a vote.

Pro-union employees at the Bessemer facility said they spent 10-hour shifts on their feet in the warehouse, where online orders are packed and shipped, and didn’t have enough time to take breaks. A union could force Amazon to offer more break time or higher pay, those workers said. Amazon, meanwhile, argued that it already offered more than twice the minimum wage in Alabama plus benefits without workers having to pay union dues.

This is the second unionizing attempt by Amazon workers in the past year.

A group of Amazon workers in Staten Island, New York withdrew its petition to hold a vote to unionize early in November. The workers, however, can refile a petition.

The organizing effort in New York City is working without the help of a national sponsor and is being spearheaded by a former Amazon employee, Christian Smalls. He said he was fired just hours after he organized a walkout last year to protest working conditions at the outset of the pandemic.