President Donald Trump’s nominee for ambassador to Russia confirmed on Wednesday that Rudy Giuliani was at the center of a smear campaign in the State Department against then-U.S. ambassador to Ukraine Marie Yovanovitch, who has become an important impeachment witness.

“My knowledge in the spring and summer of this year about Mr. Giuliani was in connection with a campaign against our ambassador to Ukraine,” John Sullivan revealed to Sen. Robert Menendez (D-NJ) at a Senate foreign relations hearing.

Sullivan said that he was also given a package of disinformation that was being circulated in the State Department to smear Yovanovitch. He indicated that the package originated from someone in the White House.

Sullivan insisted that he turned the package over to the inspector general after he was not able to determine who created it.