(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 was losing a bid to organize 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 last year. The most recent outcome is pending in light of hundreds of challenged ballots and now the RWDSU’s objections, which could delay a result for months.

Amazon spokesperson Kelly Nantel said, “We want our employees’ voices to be heard, and we hope the NLRB counts every valid vote.”

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 result.

Amazon itself took issue with the RWDSU’s conduct, such as the union’s communications with workers around the use of a mailbox on warehouse property, adding that its filing objections is standard process.

The retailer faces a high bar in demonstrating that the New York union violated rules for engagement with employees that influenced the outcome, said John Logan, a labor professor at San Francisco State University.

In addition, the NLRB typically treats employers’ alleged violations more seriously than alleged wrongdoing by unions because companies have greater power over workers, he said.

“It’s going to be really tough” for Amazon, 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)