Can a doctor refuse to see a patient for political reasons?

A urologist in Florida posted the following sign on his door: “If you voted for Obama, seek urologic care elsewhere. Changes to your healthcare begin right now. Not in four years.” Dr. Jack Cassell claims that he wouldn’t actually refuse to treat anyone, but hopes that certain people will read the sign and voluntarily go somewhere else.

What do you think? Should he be able to do this? And how would you react if you were referred to him, whether or not you support the Obama health care plan?