Amazon’s plan to offer one-day delivery has a union that wants to represent warehouse workers crying foul.

The internet retail behemoth on Friday said it will soon promise its Prime members they’ll get their orders in a day.

In response, the Retail, Wholesale and Department Store Union, which is trying to unionize Amazon workers in various spots around the country, said warehouse workers already struggle to handle 200 to 300 orders per hour in 12-hour shifts with the promise of two-day shipping.

“If Amazon plans to effectively double the speed, it must also address existing workforce needs and ensure its workers are safe, ” Stuart Appelbaum, the union president, said in a statement. “Increasing fulfillment speeds means they need to hire more workers, under more sustainable speeds that don’t put worker’s lives in jeopardy.”

Amazon’s Dave Clark, senior vice president of worldwide operations, dismissed Appelbaum’s remarks and accused the union leader of continuing to “spout falsehoods.”

“We appreciate his concern for our associates but his concern is misguided and self-serving,” Clark said in a statement to CNN.