I think it may be more simple than that --- the GOP has simply not fielded a good candidate.
1992 - George H.W. Bush
1996 - Bob Dole
2000, 2004 - George W. Bush
2008 - John McCain
2012 - Mitt Romney
Do any of them strike you as great candidates? Bob Dole was arguably the worst candidate either party has fielded since Reagan.
Whatever one's take on W's ability to govern, I fail to see how one can seriously argue that he wasn't a great campaigner. He was folksy, able to create a sense of connection with voters, and had an apparent skill at ad libbing. (Whether he actually connected or ad libbed is irrelevant. When it comes to campaigning, perception is all that matters.) As a campaigner, he easily is the best the GOP has had since Reagan, and arguably he was as good as Reagan on the campaign trail. It wasn't just the machinations of Karl Rove that got Dubya elected and reelected to the White House.
