President Donald Trump’s lawyer, Rudy Giuliani, defended the President’s political attacks against special counsel Robert Mueller’s investigation into the Trump campaign, suggesting that the origins of the probe are illegitimate.

Asked by CNN’s Dana Bash on Sunday whether there was a larger strategy to undermine the investigation at play, Giuliani said he “couldn’t do it if they didn’t have the material.”

“They’re giving us the material to do it. Of course, we have to do it in defending the President. To a large extent, remember Dana, what we’re doing here, it is the public opinion, because eventually the decision here is going to be impeach or not impeach,” Giuliani said on CNN’s State of the Union.

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Giuliani also suggested that the start of the Muller probe was illegitimate, citing fired FBI Director James Comey’s leaked memos and a lack of evidence of collusion between Trump and Russia.

“(Y)ou get the Comey thing, which is the leak of a confidential memo, which is illegal for an FBI official to do. I’m not saying Mueller is illegitimate. I’m saying the basis on which he was appointed was illegitimate,” Giuliani remarked.

Asked whether the Mueller probe was legitimate now, Giuliani said, “not anymore,” citing reports of an FBI informant within the Trump campaign as one of the reasons for its discrediting.

The former New York City mayor also said the President is “adamant” about doing a sit-down interview with Mueller.

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Giuliani said two topics were likely to be addressed during the interview: collusion and obstruction of justice. He said he wasn’t comfortable with an interview addressing obstruction because the President could be implicated over an interpretation of a comment he made about firing Comey.

“If you interpret his comment about firing … Comey … If you interpret that as obstructing the investigation, as opposed to removing a guy who was doing a bad job, on the recommendation, in part, of (Deputy Attorney General Rod) Rosenstein, but you see it as obstructing the investigation, then you can say it is obstruction,” Giuliani told CNN. “And then you can say it is perjury, which is even easier for them, which is where I think, if they are sneaky, they are going.”