Attorney General Eric Holder on Tuesday fended off Republican demands that he appoint a special counsel outside of the Justice Department to look into national security leaks.

Holder said both he and FBI Director Robert Mueller have already been interviewed by the FBI as part of a fast-moving Justice Department leak investigation.

At a Senate Judiciary Committee hearing, Sens. Lindsey Graham, R-S.C., and Chuck Grassley, R-Iowa, said they want the attorney general to appoint a special counsel to look into the leaks, rather than Holder's choices, U.S. Attorneys Ron Machen and Rod Rosenstein, who hold political appointments.