Among the outsiders, John McCone, a California shipbuilder installed by President John F. Kennedy after the Bay of Pigs disaster, has generally been given high marks. Mr. McCone is credited with correctly predicting that the Soviet Union would deploy offensive missiles in Cuba. The agency also delivered increasingly grim reports to the White House about the Vietnam War, to the dismay of both Kennedy and President Lyndon B. Johnson.

Image Members of the Iraq Study Group, Leon E. Panetta, right, and Vernon E. Jordan Jr., at a hearing on Capitol Hill in 2006. Credit... Doug Mills/The New York Times

By contrast, Richard Helms, a careerist who ascended the ranks to take over the C.I.A. under Johnson and President Richard M. Nixon, was highly regarded inside the agency, but was ultimately blamed for the fallout from dozens of C.I.A. covert operations abroad that went sour.

In describing the rationale for turning to Mr. Panetta, aides to Mr. Obama said it was important to bring clarity to the division of responsibilities among American intelligence agencies, and in particular to end the current disputes between the offices of the C.I.A. director and the director of national intelligence.

Because Mr. Panetta does not have a C.I.A. background, the aides said, he may be less likely to instinctively defend the C.I.A.’s turf against other spy agencies. They said Dennis Blair, the retired admiral who has been tapped to become director of national intelligence, had played a role in choosing Mr. Panetta, but would have the clear mandate from the White House to set intelligence policy across the 16 intelligence agencies.

In expressing disapproval about the choice of Mr. Panetta, Mrs. Feinstein recalled that she had said that an intelligence professional would be the best choice to lead the agency now. In softening her stance on Tuesday, the senator told a reporter that the choice might be more palatable if Mr. Kappes, the No. 2 official, remained in his job. Mr. Kappes left the agency in 2004 after a clash with Porter J. Goss, then the C.I.A. director, but agreed to return in 2006 under a new director, Michael V. Hayden, in a move that lifted morale among clandestine officers.

A C.I.A. spokesman declined to comment about whether Mr. Kappes had decided to stay in his current job.