Or a decision by the U.S. Supreme Court.
So explain how it gets changed by an executive order? like Trump claims.
At best, you have the GOP majority in Congress enacting ordinary immigration legislation interpreting the 14th Amendment, which is then challenged all the way to the USSC with long odds of overturning 125 year old law. You certainly don't have the resident White House nincompoop drafting an executive order - presumably with the assistance of that "stable genius" Stephen Miller - to exclude citizenship for millions of people.