(Reuters) -Amazon.com accused the new union at a New York City warehouse of threatening workers unless they voted to organize, an assertion an attorney for the labor group called “really absurd.”

A second labor group, the Retail, Wholesale and Department Store Union (RWDSU), which lost a bid to organize at an Amazon warehouse in Alabama, also filed objections on Thursday to that union election.

The U.S. National Labor Relations Board (NLRB) is giving Amazon until April 22 to back up its objections to last week’s election in New York, in which Staten Island workers voted to form the company’s first U.S. 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 in the election at Amazon’s JFK8 warehouse in the New York City borough of Staten Island opted to join the Amazon Labor Union (ALU), which has demanded higher pay and job security. Since the result, U.S. workers from another 50 Amazon sites 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.”

Separately on Thursday, the RWDSU objected to the election in Bessemer, Alabama, in which Amazon workers voted against unionizing. It was the second election in Bessemer, after the NLRB determined that Amazon had improperly interfered in the first contest there. The most recent contest’s outcome is pending in light of hundreds of challenged ballots and now the RWDSU’s objections, which could delay a result for months.

In a filing, the RWDSU said Amazon unlawfully removed pro-union literature from non-work areas and terminated an employee who spoke in favor of the union during mandatory work meetings, among other objections. The RWDSU said these were grounds for the NLRB to set aside the election result, as occurred last year at the Alabama facility.

Amazon did not immediately respond to a request for comment on the objections.

The retailer faces a high bar in demonstrating that the New York union 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 in New York, he said.

(Reporting by Jeffrey Dastin in Palo Alto, California, Julia Love in San Francisco and Nivedita Balu in Bengaluru; Editing by Chris Reese, Jonathan Oatis and Leslie Adler)