In the Russell Senate Office Building Caucus Room, Fred McClure was watching the crowd. It was March 1978, and the American Agriculture Movement — a pressure group for government support of farm prices — was meeting with Texan congressmen. A legislative aide to Sen. John Tower (R.), McClure was leaning on a door when a rancher from Paint Creek, Texas, named Rick Perry walked past. Newly retired from the Air Force, Perry held a degree in animal science from Texas A&M. His class ring gave him away. Spotting the ring, McClure, a fellow Texas A&M grad, introduced himself, and the...