During FDR's administration our immigration laws were passed. Arizona did not change anything, they just started enforcing a federal law that the goverment was not enforcing. Arizona is just obeying the law. President Obama, Clinton as well as Bush refused to enforce it (thus they broke the law). Once again, just enforce the laws already in place, and close the border if needed. You do not need a fence for all its length, most of the unprotected area's are arid desert, fairly easy to patrol with aircraft.
This law is not a republican or democratic issue, never was, just everyone ignored it..