While the Constitution allows the federal government to make a rule for foreigners who immigrate here to become citizens, it has no authority over foreigners who are NOT citizens....what we call 'illegals'.
These are what the Founders referred to as denizens, and they are under the authority of the states.
The common law has affixed such distinct and appropriate ideas to the terms denization, and naturalization, that they can not be confounded together, or mistaken for each other in any legal transaction whatever. They are so absolutely distinct in their natures, that in England the rights they convey, can not both be given by the same power; the king can make denizens, by his grant, or letters patent, but nothing but an act of parliament can make a naturalized subject. This was the legal state of this subject in Virginia, when the federal constitution was adopted; it declares that congress shall have power to establish an uniform rule of naturalization; throughout the United States; but it also further declares, that the powers not delegated by the constitution to the U. States, nor prohibited by it to the states, are reserved to the states, respectively or to the people. The power of naturalization, and not that of denization, being delegated to congress, and the power of denization not being prohibited to the states by the constitution, that power ought not to be considered as given to congress, but, on the contrary, as being reserved to the states.
St. George Tucker
Until these rights are attained, the alien resident is under some disadvantages which are not exactly the same throughout the Union. The United States do not intermeddle with the local regulations of the states in those respects. Thus an alien may be admitted to hold lands in some states, and be incapable of doing so in others. On the other hand, there are certain incidents to the character of a citizen of the United States, with which the separate states cannot interfere.
William Rawle
And Jefferson used “Separation on Church and State” in a letter to the Danbury Baptists. That wasn’t in the Constitution, either.
What does that have to do with the EXPLICIT responsibility of the Federal Government to protect against invasion?