I agree that those religious groups represent the core of the GOP's social-conservative wing, but I don't think they have the numbers to dominate it -- there are only about six million Mormons and less than a million Orthodox Jews in the US, not all of which are guaranteed to belong to the GOP (although most do). It's harder to count conservative Catholics or evangelical Protestants, since those groups don't map directly to religious affiliation, but some parts of those demographics seem to have high rates of attrition between generations.