TAMPA, Fla. — As the Republican race moves to a state defined by the extremes in recession-era America — where the underwater and unemployed live just a few miles from the 1 percent — a sharp class divide is emerging between the two top contenders. Mitt Romney’s crowds look like something out of the president’s suite at a University of Florida football game — prosperous, trim, Tattersall-clad, and supportive but not rowdy. Newt Gingrich supporters, with their spray-painted signs, American flag tees, flip-flops and fanny packs, more closely resemble a group that would fit in nicely playing a few bucks...