With one exception, in every Presidential election since 1952, the Republicans have had Richard Nixon, George Bush, or Robert Dole on their ticket. The exception was 1964, with Barry Goldwater and William Miller, which also produced the largest fraction of the popular vote for a candidate in U.S. history (61%, for Johnson-Humphrey).
All the Republicans currently running for President, with the exception of John McCain, are either Doles, Bushes, or symbolic. By symbolic, I mean a candidate with no track record in elected or cabinet positions. (That’s not supposed to be a slam; I’m sure Keyes, Buchanan, and Forbes are very sincere, but none of them stands a chance in any party.)