If a law is on the books, it should be enforced. I propose passing a law that allows local governments to enforce any laws which higher levels of government refuse to enforce, after a given time.
If the federal law forbids illegal border crossings, and the federal government refuses to enforce that law, then the states should have the right to enforce it when the federal government refuses to. If the states refuse to enforce a law on their books, then the counties and cities should be able to enforce that law instead. This will help limit the damage that another negligent administration could do.