Good point on Levin's part.
Basically the Obama Regime is taking the point of view that they are exceeding their authority, basically denying a state has any right to enforce laws on its books related to immigration that are not in conflict with Federal statutes. Since AZ is merely trying to live up to their end of the deal and aiding the Federal government at the same time in executing its own laws, drawing the conclusion AZ is in conflict with Federal statutes is DOA, but stubbornly The Regime clings to the belief in Almighty Centralized Power trumps uppity states. Pretty piss-poor argument, that! But yet one more revealing look behind the Left's statist curtain.