If that's the best exapmple you've got, then maybe Simon's your man.
In 1976, Reagan nearly cost an incumbent President the nomination of his own party -- that's a significant success. (Although the Arlen Specter VP offer was sad).
But you can read the other's comments, as to how Simon took a race that should have been won and lost it!!
Plus, I gave you the Jeb Bush comparison, which is more like Simon's situation.