President Barack Obama is asking Congress to extend the term of Federal Bureau of Investigations Director Robert S. Mueller III for two years. Mueller was sworn in as the head of the F.B.I. just seven days before the terrorist attacks on Sept. 11, 2011 – an event that marked the greatest challenge ever for the nation and the bureau’s 93-year history. Mueller has led the FBI in preventing attacks like the Christmas Day shoe-bomber and stopping al-Qaida operative Najibullah Zazi who was headed for New York City in 2009 to blow himself up. For more on how Mueller changed the FBI and who might be qualified to replace him, we talk with Barton Gellman, contributing editor at large for Time Magazine, a research fellow at NYU’s Center on Law and Security, and author of “Angler: The Cheney Vice Presidency.” He wrote an article on Mueller and the future of the FBI for this week’s Time Magazine. Mueller, himself, did not intend of staying in this post for the full ten years; he even wrote out his letter of resignation to President George W. Bush in 2004 when the president authorized, without a warrant, a surveillance program the Justice Department deemed illegal. But Bush rejected the resignation and ultimately sided with the Justice Department to keep Mueller on board.