Through his mother, Cruz was an American citizen at birth, just NOT a NBC, since his father didn’t become an American citizen until 2005.
From Ilya Shapiro with the CATO institutes (why ask leftist what they think, they don't respect the Constitution.) http://www.freerepublic.com/focus/news/3060736/posts
“What's a “natural born citizen”? The Constitution doesn't say, but the Framers’ understanding, combined with statutes enacted by the First Congress, indicate that the phrase means both birth abroad to American parents "in a manner regulated by federal law" and birth within the nation's territory regardless of parental citizenship. The Supreme Court has confirmed that definition on multiple occasions in various contexts.”
I am surprised that Rush did not know the difference between citizenship and natural born citizen. I hope someone clues him in.