http://www.boston.com/news/nation/w...07/18/reporter_ties_cheney_aide_to_cia_story/ WASHINGTON -- I. Lewis ''Scooter" Libby, Vice President Cheney's chief of staff, was a second source for a Time magazine article that revealed the identity of a covert CIA agent, the magazine reported yesterday, undercutting repeated White House denials. For two years, the Bush administration has said that neither top presidential adviser Karl Rove nor Libby was involved in identifying Valerie Plame, the covert CIA agent first named in a July 2003 article by syndicated columnist Robert Novak. Last week, Rove, Bush's deputy chief of staff, was identified as a confidential source of Time reporter Matthew Cooper and that disclosure led to some Democrats calling for Rove's resignation while others pressed for the revocation of his security clearance. The disclosure also resulted in the White House no longer denying Rove's involvement and instead declining to comment because the matter is under investigation. The partisan attacks are expected to continue this week with Libby -- a neoconservative and member of the team planning for the war -- being linked again to the story, and as Congress hears testimony backing a federal shield law to protect reporters from testifying about unnamed sources. It was reported last year that Libby waived a confidentiality agreement with Cooper, allowing him to give testimony, but the topic of their conversation was not known. Republicans continued yesterday to defend Rove. Republican National Committee chairman Ken Mehlman, appearing on NBC's ''Meet the Press," argued that Rove learned of Plame's identity from journalists, and that Democrats are attacking Rove based on information that exonerates Rove. Mehlman said Democrats owe Rove an apology. A lawyer familiar with Rove's grand jury testimony told the Associated Press yesterday that Rove learned about the CIA officer either from the media or from someone in government who said the information came from a journalist. The lawyer spoke on condition of anonymity because the federal investigation is continuing. Also appearing on ''Meet the Press," John Podesta, chief of staff during the Clinton administration, said if Rove had ''an ounce of character," he would resign. ''Mr. Rove has created a tremendous credibility problem for this White House, for this president, for this country on a matter of utmost national security," he said. ''The one thing that is unassailable at the end of this week is that Mr. Rove did not tell the truth in 2003."