Seems to me that ending birthright citizenship should be easy. The 14th amendment´s language includes: “ and subject to the jurisdiction thereof”...
All congress has to do is pass a law that defines “ and subject to the jurisdiction thereof” to mean that unless you´re a citizen or in the country legally, the jurisdiction clause doesn´t apply to you. Then explicitly state that at least one of the birth parents need to be in the country legally or citizenship isn´t conveyed.
The 14th Amendment was about granting citizenship to freed slaves. Period.
You realize that if theyre not subject to US jurisdiction we cant arrest and prosecute them, right?