Amazon accused a new union at one of its New York warehouses of threatening workers unless they voted to organize, an assertion an attorney for the labor group called “really absurd.”

The National Labor Relations Board is giving Amazon until April 22 to back up objections to last week’s election, in which Staten Island workers voted to form the company’s first American union. Amazon had requested extra time to provide evidence because its objections are “substantial,” it said in a filing Wednesday.

A certified election result would give organized labor a foothold in the United States’ second-largest private employer, with the potential to alter how Amazon manages its finely tuned operation.

Some 55% of workers who voted at Amazon’s JFK8 warehouse in Staten Island opted to join the Amazon Labor Union, which has demanded higher pay and job security. Since the result, US workers from another 50 buildings have contacted the union, the group’s leader has said.

Among Amazon’s planned objections to the outcome are that the ALU interfered with employees in line to vote and that long waits depressed turnout, Amazon’s filing said. Some 58% of eligible voters cast ballots in person over several days.

Eric Milner, an attorney representing the ALU from law firm Simon & Milner, dismissed Amazon’s claims as false and said they would be overruled.

“To say that the Amazon Labor Union was threatening employees is really absurd,” he said. “The Amazon Labor Union is Amazon employees.”

The ALU has filed various unfair labor practice charges against Amazon’s conduct.

The retailer faces a high bar in demonstrating that the ALU not only violated rules for engagement with employees, but that those violations influenced the outcome, said John Logan, a labor professor at San Francisco State University. The NLRB also typically treats employers’ alleged violations more seriously than alleged wrongdoing by unions because companies have greater power over workers, he said in a telephone interview.

“It’s going to be really tough” for Amazon, he said.