U.S. President George W. Bush said on Wednesday he would withhold judgment on the role of his top political adviser, Karl Rove, in a brewing controversy over who leaked a CIA agent's identity until a federal investigation is completed. With Rove seated behind him as he took questions from reporters during a Cabinet meeting, Bush said there was a "serious investigation" under way into who leaked the identity of covert CIA agent Valerie Plame, according to Reuters. "I have instructed every member of my staff to fully cooperate in this investigation. I also will not prejudge the investigation based on media reports," Bush told reporters in response to a question. "We're in the midst of an ongoing investigation and I will be more than happy to comment further once the investigation is completed," Bush said.