The GOP began to die when Bush the Elder tried to make it a "kinder, gentler" party--in another words, a "pale" replica of the Democratic Party. The core of the Republican vision--individual rights, personal liberty, free markets, limited government, self-reliance, honest dealing--was befogged by the patriarchal "noblesse" class. We are still chasing the rabbit 20 years later, and we always will be, only getting further and further behind, until we get our act straight. In my view GHWB was sent to make sure that Reagan didn't "go too far."
By the bye, I think the "conservative" arm needs a new name, something more dynamic than "conservative," which to me at least implies a defensive posture.