From the Associated Press:
... Defense Secretary Donald Rumsfeld and top military officers were to testify Thursday before Congress, already bitterly divided over the war. In addition, fresh reports have said that up to two-thirds of the Army's combat units are unprepared for wartime missions because of the strain of operations in Iraq.
Rumsfeld had said Wednesday he essentially was too busy to testify before the Senate Armed Services Committee and would instead attend a private briefing with the entire Senate on Thursday.
He changed his mind after hours of criticism and pressure from Senate Democrats, including Sen. Hillary Rodham Clinton of New York, who said the Pentagon chief should be accountable to the public by answering questions on the war.
The Pentagon offered no reason for Rumsfeld's change of plans.