I believe that Ted Cruz has a large support segment among social conservatives. I would also not count him out among reasonable libertarians.
Huckabee and Santorum are yester-year's news... tried and failed. Cruz is dynamic and interesting.
Cruz is the tea party favorite but as others have pointed out he is quite popular with most social conservatives and if Huckabee/Santorum fall out then he will get their votes. His limited government and Federalism are very appealing to the libertarian Republicans and young independents. A lot of Ron Paul voters could like Ted Cruz. And the dirty secret that the GOP-E and the media don’t want anyone to know is that if Cruz got the nomination most of the establishment GOP voters would vote for him as well. 90% of GOP-E voters (and there are lots of them will vote anyone with an (R) especially if the Rats run a real liberal. A lot of Wall Street and Chamber of commerce money may not go to Cruz rather than a RINO but that is separate issue from actual voters.