Story highlights Rep. Adam Schiff said he believes that Comey's firing was "all about the Russia investigation"

Schiff: "Shifting" stories by Trump administration on reasons for firing enhance the need for thorough investigation

(CNN) Acting FBI Director Andrew McCabe said President Donald Trump hasn't made any effort to impede the investigation into possible ties between his campaign and Russia -- but a top House Democrat disagrees.

"I don't think you can say so categorically he's made no effort to interfere," Rep. Adam Schiff, the top Democrat on the House Intelligence Committee, said in an interview with CNN's "Erin Burnett Outfront" Thursday night.

"I think that the firing was all about the Russia investigation," he continued. "So I'm certain that what Mr. McCabe said may be true in the sense that the President isn't calling line agents who are working on the investigation or, in other very ham-handed ways, trying to interfere with the day-to-day operation of the investigation."

"But nonetheless, he fired the top cop on that investigation, and I think no one believes this was about Hillary Clinton's emails, I think it was all about the Russia case," Schiff said.

Trump told NBC on Thursday that he wanted the FBI's investigation into Russia's election meddling to be "absolutely done properly," and said Comey's firing might "lengthen out the investigation." White House deputy press secretary Sarah Huckabee Sanders suggested earlier that it could hasten the agency's investigation.

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