Spicer apologized for his remarks after making them at a White House briefing Tuesday. But that hasn't placated several Democrats, including New Jersey Rep. Donald Payne Jr., who on Wednesday called Spicer's remarks "disgusting and inane."
"It is beyond comprehension that a White House spokesman would make such disgusting and inane comments downplaying the atrocities of the Holocaust," he said in a statement. "Spicer obviously has no business speaking from the White House podium. It's clear that he must resign or be fired immediately. The American people deserve an apology and a denouncement of these comments from the President."
, Rhode Island Democratic Rep. David Cicilline, who is Jewish, also asked for Trump to terminate Spicer as press secretary, calling his comments "despicable, ignorant remarks."
Earlier Tuesday, House Democratic leader Nancy Pelosi had also called for Trump to fire Spicer.
"While Jewish families across America celebrate Passover, the chief spokesman of this White House is downplaying the horror of the Holocaust," she said in a statement. "Sean Spicer must be fired, and the President must immediately disavow his spokesman's statements. Either he is speaking for the President, or the President should have known better than to hire him."
Spicer, in an effort to shame Russia's alliance with Syrian President Bashar al-Assad and his use of chemical weapons, said Tuesday that Hitler "didn't even sink to using chemical weapons" during World War II.
Hitler didn't use chemical weapons on the battlefield, but he and the Nazis used gas chambers to exterminate Jews.
"You had someone who was despicable as Hitler who didn't even sink to using chemical weapons," Spicer said. "So you have to, if you are Russia, ask yourself is this a country and a regime that you want to align yourself with."
Speaking Wednesday on CNN's "New Day," Steven Goldstein, the executive director of the Anne Frank Center for Mutual Respect, said Spicer's apology didn't go far enough.
"He's got to leave," Goldstein said. "President Trump has got to fire Sean Spicer."
CORRECTION: A previous version of this story incorrectly identified the Anne Frank Center for Mutual Respect.