Republicans are not necessarily Libertarians.
In particular, Bush was not a Libertarian.
He spent recklessly, engaged in chicanery to promote useless and costly wars, trampled all over civil liberties, cut protectionist deals with the steel industry and others, and screwed up big time on immigration.
As far as I know, Libertarianism is not primarily defined as a dogmatic belief in total deregulation (at least I hope it is not).
Libertarians tend to believe that victimless crimes are not actually crimes, that national borders should be much more open than they currently are, that foreign military operations are rarely justified, and that people have a right to privacy.
The idea that government screws things up is more an idea from Public Choice than from Libertarianism. Even if the government was awesome at fighting wars, Libertarians would oppose it. I think most Libertarians are *happy* that the government is not particularly good at what it does.
To me, Libertarianism is a philosophical argument against a lot of government interventions, and Public Choice is an instrumental argument against a lot of government interventions.
In case you are wondering what set me off,
check here.