Because only the democrats have seen the light? Just because republicans pander to ensure they get votes from a certain base does not mean all republicans are fundamentalists. Some of us vote republican because there isn't a viable libertarian candidate.
Ah, but not all AKP voters are Islamist. The similarity is that both are primarily a union of social conservatives and pro-business voters (primarily -- Libertarianism as such isn't really common in Turkey from what I've seen, and analogies are rarely perfect.)
But if you don't think that the discourse in the Republican party isn't heavily influenced by Christianists...
(And the two countries' opposition parties are quite different.)