Congressional Democrats are seizing on Sean Spicer's claim that Adolf Hitler did not use chemical weapons during World War II, calling the White House press secretary's remarks offensive and suggesting he brush up on his history.

House Minority Leader Nancy Pelosi (D-Calif.) called on Spicer to be fired, accusing him of "downplaying the horror of the Holocaust." "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," she said in a statement. ADVERTISEMENT Rep. Rep. David Cicilline (D-R.I.), who is Jewish, also called on Spicer to resign, saying “Donald Trump’s White House does not get the benefit of the doubt when it comes to anti-Semitism." “It’s time for some real accountability in this White House. And it should start with Sean Spicer’s resignation.” Spicer told reporters on Tuesday that "you had someone as despicable as Hitler, who didn’t even sink to using chemical weapons," even though Hitler is known to have used cyanide gas in the mass murders of Jews. Spicer appeared to be drawing a contrast between Hitler and a chemical attack that killed dozens of Syrians earlier this month and has been linked to Syrian President Bashar Assad. But Spicer's claim sparked near immediate backlash from congressional Democrats and the media. Ed Markey Edward (Ed) John MarkeyMassachusetts town clerk resigns after delays to primary vote count Bogeymen of the far left deserve a place in any Biden administration Senate Democrats urge Amazon to recall, stop sales of explosive products MORE No Senate Democrat has publicly called on Spicer to either be fired or resign yet, but Sen.(D-Mass.) appeared to be the first senator to publicly call on Spicer to apologize. "Absolutely shameful and offensive. Mr. Spicer needs an history lesson and should apologize," Markey tweeted on Tuesday after the White House news briefing.

Spicer has offered multiple clarifications to his original comments.

When a reporter asked him during the press briefing if he wanted to follow up on his comments, Spicer said that Hitler "was not using the gas on his own people the same way" and that he "brought them into Holocaust centers."

He added in a later statement that he was "in no way trying to lessen the horrendous nature of the Holocaust."

"I was trying to draw a distinction of the tactic of using airplanes to drop chemical weapons on population centers. Any attack on innocent people is reprehensible and inexcusable," he added in another statement to reporters.

But that has done little to stem the flow of criticism over his original remarks.

Cardin also took a swipe at Spicer's comments about "Holocaust centers," adding on Twitter: "Really? The term you were looking for was concentration camps." Sean Spicer: Really? The term you were looking for was concentration camps. — Senator Ben Cardin (@SenatorCardin) April 11, 2017

Sen. Brian Schatz (D-Hawaii), who was the first Democratic senator to weigh in on Twitter, questioned if Spicer "should get the benefit of the doubt."

I find nothing funny about the Press Secretary bungling holocaust history. Because I'm not sure they should get the benefit of the doubt. — Brian Schatz (@brianschatz) April 11, 2017

Several House Democrats also quickly piled on, taking to Twitter to express outrage over Spicer's comments.

Rep. Linda Sánchez called Spicer's remarks "unhinged from reality" in a tweet.

Sean Spicer's dismissal of the Holocaust’s atrocities is disgusting. His comments are unhinged from reality. https://t.co/RG1p57fLsA — Linda T. Sánchez (@RepLindaSanchez) April 11, 2017

Rep. Kathleen Rice (D-N.Y.) said making a Hitler comparison was simply unnecessary.

“No reason to call one mass murderer less despicable than another. Use of chemical weapons against anyone is an atrocity. Period,” Rice tweeted.

Rep. Donald Payne (D-N.J.) questioned if they could swap out Spicer for Josh Earnest, a former press secretary in the Obama administration.

“Never thought I would say this, but Sean Spicer should go back to talking about crowd size at the inauguration,” Schiff tweeted

Cristina Marcos contributed.

Updated 5:07 p.m.