Filling a Vacuum. For the G.O.P., 1968 may represent the best opportunity in years—but the party has earned a reputation for booting such opportunities away. The late Sam Rayburn once said: “Just leave the Republicans alone and they’ll manage to screw it up every time.” As Esquire magazine noted this month: “The Republican Party could probably beat Lyndon B. Johnson in 1968 if it did not have to run a candidate against him.” The more likely it seems that Lyndon Johnson can be defeated, the more tempted the G.O.P. may be to blow its chances by putting up a candidate who is acceptable to the party pros rather than to the electorate.