CNN anchor Jake Tapper criticized Democrats for their rush to trust Giuliani associate Lev Parnas since he has a "serious credibility issue."

Parnas has spoken out publicly for the first time since the Ukraine scandal emerged last year and laid heavy charges against President Trump, accusing him of having direct involvement in the push to withhold aid to Ukraine in exchange for an announced investigation into the Bidens' ties to Burisma during an interview on MSNBC that aired Wednesday night.

Trump denied knowing Parnas outside of interactions at fundraisers.

While several Democratic lawmakers have sounded the alarms on Parnas' allegations against the president, Tapper urged caution.

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"We can't ignore -- Parnas has a serious credibility problem," Tapper told a panel on Thursday. "He's under indictment for campaign finance charges. The foreign minister of Ukraine told CNN's Christiane Amanpour that he doesn't trust a word Parnas is saying."

He continued, "And yet, I see people out there on social media -- Democrats -- acting as if this guy is the second coming of Theodore Roosevelt or something."

The "State of the Union" moderator acknowledged that the "broad contours" of Parnas' claims are not "out of nowhere," pointing to the rough transcript of Trump's phone call with Ukrainian President Volodymyr Zelensky where the president cited his personal attorney Rudy Giuliani.

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"It's just the specific references to 'Pence knew, Barr knew, Trump knew.' How would he know?" Tapper added.