Fox News contributor Marc Thiessen slammed CNN Monday over the liberal network's response to revelations one of their freelance writers, Adeel Raja, had praised former leader of Nazi Germany Adolf Hitler on social media.

Thiessen questioned CNN's judgement on its associations while appearing on "America's Newsroom," telling hosts Bill Hemmer and Dana Perino, "You'd think they'd do better due diligence."

"A writer, apparently a freelance contributor as it’s described, gentleman by the name of Adeel Raja. I don’t know if you’ve heard of him. I have not. He apparently sent out a number of tweets. Here's one of them: ‘The world today needs a Hitler,’" Hemmer began. 

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Hemmer read CNN's statement about Raja that he had only been a freelancer and would not work again with CNN again, asking Thiessen what he took from its response.

"Well, first of all, it’s not just he contributed a couple of things here and there. He wrote 54 articles for CNN, so it's not like he had a tenuous connection to CNN," Thiessen said. "Second of all, this is not new. This is not related to this conflict. In 2014 he tweeted out ‘Hail Hitler,' and he said he was supporting Germany in the World Cup because Hitler was a German and he did a good job with those Jews. CNN didn’t notice that back in 2014?"

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"You'd think they'd do better due diligence on their contributors. At least they got rid of him," he continued. "Ilhan Omar and Rashida Tlaib, who are virulent anti-Semites, are still on their committees in Congress. Maybe the Democrats ought to take a lesson from CNN and get rid of the anti-Semites in their ranks." 

Raja's now-deleted tweets came to light Sunday as multiple networks, including Fox News, reported their contents amid the violence playing out between Hamas, a Palestinian terrorist organization, and Israel.

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Thiessen's reference to far-left "Squad" members Rep. Ilhan Omar, D-Minn., and Rep. Rashida Tlaib, D-Mich., concerned their past anti-Semitic statements towards Israel and its supporters, which received widespread condemnation, including from their fellow Democratic members of Congress