The US Constitution enumerates the specific power of Congress to establish the rules of naturalization per Article 1 Section 8 clause 4. The “rules of naturalization” includes any and all rules including who is a citizen at birth and what conditions have to be met in order to be born a citizen (naturally born).
Congress expresses it’s will via several acts known as the naturalization acts as well as amendments to the constitution and modified by various laws. The collective sum of these is known as United States Code (USC)
The current law with regards to citizenship at birth can be found in title 8 section 1401. Under subsection G, Sen Cruz was born a US citizen and has never needed to be naturalized. Thus, he is naturally born a US citizen.
Further backing that point is Title 8 section 1481 which specifically says naturalization can only be applied AFTER birth.
I would advise you that these continued attacks on conservatives will not aid Trump in his attempt to win the general election. Further, continuing such attacks could very likely cost him the election. The Trump camp is often saying that to not support their candidate is helping to elect Hillary. I would also point out that attacking voters that COULD vote for Trump is only going to piss them off - and by absence of their votes, elect Hillary.
The US Constitution was written by men knowledgeable and strongly influenced by Vattel’s Law of Nations. The Law of Nations is the source of Natural Born Citizen and Cruz does NOT qualify!
“...these continued attacks on conservatives...”
Translation: Justified, fact-based, condemnations and criticisms of Ted Cruz.
This video might help you in deciphering whether Cruz is a NBC ( he certainly is not)
http://powderedwigsociety.com/eligibility-of-cruz-and-rubio/