Amazon has lost the first round in its effort to overturn a historic union victory at a Staten Island facility.

A National Labor Relations Board officer who heard Amazon’s objections recommended that the vote be upheld.

In April’s closely watched election, warehouse workers at the Staten Island facility known as JFK8 voted to form the first US union in Amazon’s 27-year history — a stunning win for a newly established organization composed of current and former warehouse employees. The union won the vote by a margin of 523 votes out of nearly 5,000 cast.

Amazon almost immediately contested the vote, filing a formal complaint to the NLRB laying out 25 objections — including allegations that the NLRB and Amazon Labor Union worked together to give union supporters an edge. Amazon also alleged the NLRB didn’t properly staff the polls during the election, creating “chaos and hours-long lines to vote on the first polling day, discouraging other employees from voting.”

Amazon’s objections were roundly rejected in Thursday’s recommendation from the NLRB hearing officer. Amazon will appeal the finding.

The hearing officer, who works with a different NLRB office than the one Amazon accused, found Amazon had not proved that the NLRB, the union or any third party “engaged in objectionable conduct affecting the results of the election.”

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“While we’re still reviewing the decision, we strongly disagree with the conclusion,” said Amazon spokesperson Kelly Nantel. “As we showed throughout the hearing with dozens of witnesses and hundreds of pages of documents, both the NLRB and the ALU improperly influenced the outcome of the election and we don’t believe it represents what the majority of our team wants.”

Amazon also argued the NLRB should have more quickly investigated what it said were “frivolous” unfair labor practice charges made and “exploited” by the union. The company also alleged the union supporters intimidated employees and “threatened violence against its detractors.”

“We believe that the actions of the NLRB and the ALU improperly suppressed and influenced the vote, and we think the election should be conducted again so that a fair and broadly representative vote can be had,” Kelly said at the time the objections were filed a week after the April vote.

Since the JFK8 vote, the union has lost a second vote at a nearby facility, and filed to have another vote at an Amazon distribution center in Albany, New York.

—CNN’s Sara Ashley O’Brien contributed to this report.

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