J.D. Hayworth, who is challenging Sen. John McCain in the GOP primary, is scheduled to speak:

Tea party activists are gathering along a remote stretch of the Arizona-Mexico border about 70 miles west of Nogales.
They’re rallying Sunday on a private ranch in support of Arizona’s controversial immigration law. A judge has put much of the law on hold.
The rally is being held near a stretch of the wall made of 15-foot steel posts set closely together to prevent people from crossing the border. People have attached flags with messages about curbing illegal immigration to the posts.