ATLANTA — Herman Cain is learning the hard way what it means to face the glare of the national spotlight. After captivating Republicans hungry for an alternative to Mitt Romney, the presidential hopeful has made a series of stumbles that have left some questioning if he's ready for the White House. The Georgia businessman has been on a media blitz since a rise in the polls catapulted him into the top tier of the race for the Republican party nomination. But Cain has sometimes appeared to be in over his head. In the last week, he: —Suggested a fence along...