CEDAR RAPIDS, Iowa – When Bernie Sanders addresses throngs of supporters who gather at his rallies, the divisions that plague the Democratic Party can feel far away. The Vermont senator speaks of building a “mutliracial, mutli-generational movement” that will cut through economic divides, catapult him into the White House and transform the nation. Some of the highest-profile surrogates campaigning on his behalf are less sanguine. Speaking at a concert for Sanders on Friday night, Rep.