appointed two U.S. attorneys to investigate leaks about details of drone attacks and special forces strikes. Critics have claimed that the White House disclosed the information to bolster the president's re-election chances.

"The notion that my White House would purposely release classified national security information is offensive," Obama told reporters during Friday press conference. "And people I think need to have a better sense of how I approach this office and how the people around me here approach this office."

But Liz Cheney on Sunday insisted that the president himself could be the one behind the leaks.

"I'd like to see an independent investigation," she told Fox News host Chris Wallace. "If you've got members of the national security team -- which is what we know from reading [New York Times reporter] David Sanger's piece, that's what he says -- giving him chapter and verse of what went on in these National Security Council meetings then somebody's got to be held accountable for, you know, what is a betrayal to the nation."

"I do think that it's important -- as Mike Rogers, chairman of the House intel committee, has said -- that whoever is looking at this needs to be outside the chain of command so that you can be absolutely sure that it is followed to it's conclusion," she added. "And that may well be the president of the United States."

"If the president of the United States has been authorizing people on his national security team to brief The New York Times about one of our most highly classified programs, the American people have a right to know."

Former Vice President Dick Cheney's then-chief of staff, I. Lewis "Scooter" Libby was convicted of perjury, obstruction of justice and lying to investigators in the probe of who leaked the identity of CIA operative Valerie Plame. The vice president pushed for a full pardon and then-President George W. Bush eventually commuted Libby's 30-month prison sentence before he ever served a day in jail.

Many have assumed that Dick Cheney masterminded outing Plame to discredit her husband, former Ambassador Joseph C. Wilson IV, because he had cast doubt on the Bush administration's rationale for war with Iraq. But the the vice president told prosecutors that "I don't recall" telling Libby about Plame's identity.