In constructing his presidential administration, Kennedy elected to retain Eisenhower's last science advisor Jerome Wiesner as head of the President's Science Advisory Committee. Wiesner was strongly opposed to manned space exploration, having issued a report highly critical of Project Mercury. Kennedy was turned down by seventeen candidates for NASA administrator before the post was accepted by James E. Webb, an experienced Washington insider who served President Truman as budget director and undersecretary of state. Webb proved to be adept at obtaining the support of Congress, the President, and the American people. Kennedy also persuaded Congress to amend the National Aeronautics and Space Act to allow him to delegate his chairmanship of the National Aeronautics and Space Council to the Vice President,