Sarah Palin, McCain’s former running mate and perhaps the most powerful brand in Republican politics, will stump for McCain in Arizona on March 26 and 27, a Palin adviser told CNN. The presence of Palin – and the considerable crowds and media attention she will draw – might give pause to J.D. Hayworth, the former Republican congressman and radio host who opposes McCain’s position on illegal immigration and is mulling a Senate run of his own.