To see why they're not crazy, start with this fact of political life: When an incumbent runs for re-election, the contest is a referendum on him. A challenger, to be successful, must offer an appealing alternative that better addresses whatever's bothering people. Jimmy Carter, the outsider, beat President Gerald Ford in 1976 in the shadow of the Watergate scandals. Ronald Reagan defeated Carter four years later by showing resolve that resonated during the Iranian hostage crisis. Bill Clinton's domestic focus had broad appeal in 1992, the first presidential contest after the end of the Cold War, against the veteran cold warrior President George H.W. Bush.