Cruz is the only one not on technical US soil. I wish he was ineligible but think that the courts would side with him by virtue of his mother's citizenship. Just like children of ex-pats are US citizens even if they are living in Paris at the time of their births. It also means that Churchill could have run for President as he was born in England but his mother was still a US citizen.
I am not a lawyer. I was born in Germany, and when I studied the Constitution in what is commonly called middle school I learned that I was born a citizen, but I was not born a ‘natural born’ citizen. To be ‘natural born’ citizen required two citizen parents born in the United States.
Lord McCain got the Senate to declare him eligible. Everybody accepted that is all it takes. I have read recently that McConnel refused to bless Cruz with eligibility. Personally I do not consider lord McCain ‘natural born’, but, some people are entitled.
Cruz's claim to fame was he was in favor of ‘original intent’ of the Constitution, except he expects to exempt himself from ‘original intent’.. If Rubio wins the nomination, Cruz cannot challenge his eligibility because Cruz is not eligible himself... I never thought I would see the day that the GOP would flaunt the Constitution so fragrantly. Going to be a wild ride.