Book excerpt: Because of the power-fearing drafters of the U.S. Constitution, the president's tools for influencing Congress are quite limited. Presidents have had to look beyond the formal powers of the office to push a legislative agenda. In Between the Branches, a book of unprecedented depth, Kenneth Collier traces the evolution of White House influence in Congress over nine adminstrations, from Eisenhower to Clinton. It will enlighten students of the presidency, Congress, and all those interested in American politics.