As a Reagan supporter who was never fond of his or any other political party I switched to Trump from Cruz very early on as Cruz hooked sharply to the left on amnesty.
Out of a vast field of candidates Donald Trump was the only actual nationalist.
To me, having a Nationalist who loves his country is vastly more important than the letter on the Jersey.
I was slower to switch from Cruz, but Amnesty and then criticism of Trump for democrats initiating violence at Trump rallies did it.