Obama's administration is suing Arizona for that state's recently passed anti-illegal immigration law. Obama's rationale is that Arizona is overstepping its limits as to what a state can and cannot do. The official line coming out of the White House is that Arizona's getting tough on illegals is something that only the federal government should be handling.
Like hell it is. The people and government of Arizona would not have had reason to take up the initiative on their own had Barack Obama, George W. Bush before him, and too damned many other politicians actually taken seriously their own pledges and oaths of office to defend the integrity of the United States.
So in effect, Obama is trying to punish Arizona for doing the job that Obama and others have failed to accomplish.
When the federal government has that kind of disdain toward a state, and legally takes sides with another sovereign country bordering that state, well...
...I don't have a hard time envisioning - and I don't have a problem with articulating the possibility of - sympathies toward succession in that state.
If the people of Arizona come to sincerely believe that the federal government does not have their best interests in mind and is in fact working against them, then why would the people of Arizona or any other state in such situation believe that they have a moral obligation to be beholden to said government?