The short answer is: because he is probably not a complete and total fraud.
“Isn’t it obvious that Ted Cruz is in it for Ted Cruz? The man had a choice–he could fight the Senate’s push for “amnesty first” immigration legislation, which he had a very good chance of killing, or he could stage a showy fight against funding Obamacare that he’d certainly lose. The first course would annoy the business backers who fund Senate and presidential campaigns. The latter course would gin up and channel conservative anger, boosting Cruz’s profile in the caucuses and primaries, without doing anyone much damage at all (since it would fail). The choice seems to have been a no-brainer for the senator.
I originally thought Cruz opposed amnesty and took a dive on the issue, doing the minimum possible to maintain his credibility. I now don’t think his behavior was that bad. It was worse–his very opposition to amnesty was fake.”
UPDATE: Trump now leads Cruz by over 8 points in his OWN NATIVE STATE!