Washington (CNN) President Donald Trump's lawyer, Rudy Giuliani, did not rule out Sunday that the President could plead the Fifth Amendment in special counsel Robert Mueller's Russia investigation.

"How can I ever be confident of that?" Giuliani told anchor George Stephanopoulos on ABC News' "This Week." He added, "When I'm facing a situation with the President ... in which every lawyer in America thinks he would be a fool to testify, I have a client who wants to testify."

Giuliani, who recently joined Trump's personal legal team to focus on interfacing with special counsel Robert Mueller in his Russia probe, said the President does not have to comply with a subpoena from the special counsel.

"Well, we don't have to. He's the President of the United States," Giuliani said. "We can assert the same privileges as other presidents have."

Mueller has raised the possibility of a presidential subpoena in at least one meeting, sources told CNN , and a version of Mueller's potential questions for the President was leaked last week and first published by The New York Times.

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