It is highly suspect that the government ended its contract with Arizona to train their police forces to enforce FEDERAL laws that pertain to illegal immigration and the culprits immediately after the Supreme Court ruling to allow for asking for identification and proof of permission to be in this country, not just live in this country.
The Constitution provides that a contract entered must be completed. This is a restriction placed on states and if any power not granted to the government falls onto the states, then the government does not have the right to end a contract simply because they don't like a law they have passed.
"No State shall....pass any....Law impairing the Obligation of Contracts..."
We the People compel you to regulate our borders for the purpose of National Security