H. R. Haldeman, President Nixon's former chief of staff, is said to have boasted: "Every president needs a son of a bitch, and I'm Nixon's. I'm his buffer and I'm his bastard. I get done what he wants done and I take the heat instead of him."

Richard Ellis explores the widely discussed but poorly understood phenomenon of presidential "lightning rods"-cabinet officials who "take the heat" instead of their bosses. Whether by intent or circumstance, these officials divert criticism and blame away from their presidents. The phenomenon is so common that it's assumed to be an essential item in...