Friday night, the Bush presidency was in grave trouble. TV reporters at the New Orleans convention center and Superdome were fairly weeping for food and water for the visibly suffering thousands, on the fifth day after Katrina hit. Saturday, the cavalry had arrived. All day, the truckloads of troops, helicopters and relief columns moved in. By nightfall, the convention center and Superdome had been evacuated, and reporters who had been howling only hours before were cheering. By Sunday, responsibility for the disaster was being shifted by Bush aides and media allies to the mayor of New Orleans and Louisiana Gov....