There are 2 ways to be a legal U.S. citizen.
1. You are naturalized through the immigration and naturalization process, or you are a minor when your parents are naturalized or were adopted as a minor by U.S. parents, etc. (Different forms or naturalization or citizenship after birth.)
2. You are born as a citizen. This is referred to as “citizenship at birth” or being a “natural born citizen”.
Article 1, Section 8 of the U.S. constitution give congress the power to set the rules that regulate naturalization. If those rules, set by congress, do not require you to be naturalized to gain citizenship, then you are a natural born citizen under the constitution and federal law.
What are the rules for naturalization vs. citizenship at birth? They can be found here.
What do these rules say about the situation of Mr. Cruz?
In short, that he is a citizen at birth…
“In general, a Child Born Outside the U.S. is a Citizen at Birth when the Child’s Parents Are Not Married to each other at the Time of Birth…IF The genetic or non-genetic gestational legal mother is a U.S. citizen at the time of birth, and the birth date is after December 23, 1952 AND… The mother had previously been physically present in the United States or one of its outlying possessions for a continuous period of at least one year.”
I hear a lot of extraneous arguments about the original intent of the founders on the definition of “natural born”. The original intent was to give congress the power to set the rules of naturalization which therefore set the rules of citizenship at birth. I don’t find it very complicated.
If I’ve strayed from the simple truth, I’d appreciate someone more knowledgeable than I to step in and comment below.