WASHINGTON (AP) _ Defense Secretary Donald H. Rumsfeld reached into the ranks of retired officers to pick a successor to departing Army chief of staff Gen. Eric Shinseki, officials said Tuesday.

The officials, who spoke on condition of anonymity, said Rumsfeld chose Peter J. Schoomaker, who retired from the Army after commanding the U.S. Special Operations Command from 1997-2000.

The selection, which has not been publicly announced and is subject to confirmation by the Senate, may raise eyebrows inside the military because it is rare for a defense secretary to bypass senior active-duty generals in favor of a retired officer to be the Army's top general.

Rumsfeld sent his Schoomaker recommendation to the White House on Tuesday for President Bush's expected approval.

Shinseki retires Wednesday after a 38-year career that included combat in Vietnam and head of U.S. peacekeeping efforts in Bosnia. Tension between Shinseki and Rumsfeld over the pace of the Army's effort to transform into a more agile fighting force dominated the final two years of Shinseki's four-year term.

Because no successor will have been nominated and confirmed by then, the vice chief of staff, Gen. John Keane, will temporarily assume Shinseki's job when he leaves, officials said.

Rumsfeld had tried to persuade Keane to take the top job but he declined for family reasons, officials said. Keane is due to retire this summer.

George Joulwan, a retired Army general who was the top NATO commander in Europe from 1993-97, said in a telephone interview that although he does not know who will be nominated to succeed Shinseki, the choice of Schoomaker would likely be an indicator of the Army's future course.

``This may be a signal of how (Rumsfeld) wants to structure the Army,'' with more emphasis on the mobility, flexibility and agility that are hallmarks of special operations forces, Joulwan said.

The Army has suffered an unusual amount of turbulence in leadership positions this year.

In April Rumsfeld fired Army Secretary Thomas White and picked John Roche, currently the Air Force secretary, to replace him as the top Army civilian official. Roche has not yet been confirmed by the Senate, so the undersecretary of the Army, Les Brownlee, is the acting Army secretary.

Rumsfeld has other key posts to fill, including a successor to Gen. Tommy Franks as commander of Central Command, which is responsible for all U.S. military operations in the Middle East and Central Asia. Franks is due to retire in July.

One candidate often mentioned for the Central Command post is Army Lt. Gen. John Abizaid.

In a related development, the Pentagon announced Tuesday that President Bush has nominated Air Force Maj. Gen. Walter E. L. Buchanan III for promotion to lieutenant general and assignment as commander of Central Command Air Forces. He would succeed Lt. Gen. Michael Moseley, who has been nominated to be the Air Force's next vice chief of staff.

Schoomaker, 57, began his Army career in 1969 as a second lieutenant. His first field assignment was in 1970 as a reconnaissance platoon leader at Fort Campbell, Ky. He was trained as an armor officer but switched to the secretive world of special operations in the late 1970s.

Born in Michigan, he graduated from the University of Wyoming, where he earned a bachelor of science degree in education administration and was a star football player.

He finished the Marine Corps Amphibious Warfare School at Quantico, Va., in 1976 and in February 1978 he became commander of the Army's 1st Special Forces Operational Detachment, the highly secretive Delta Force that specializes in counterterrorism missions. He held that command until 1981.

While with Delta Force he participated in the April 1980 failed attempt to rescue American hostages in Tehran.

He later was commander of the Army Special Operations Command and the Joint Special Operations Command, both at Fort Bragg, N.C.