BARACK OBAMA won’t soon be confused with Mitt Romney. But once you peel away their ideological differences, the two candidates have a similar message: Washington is broken, and I can fix it. Romney fancies exactly that language, touting his corporate background and success in righting the 2002 Salt Lake City Olympics, while Obama promotes himself as a “post-partisan” candidate who will move beyond the squabbles and grudges of the Baby Boom generation and create “a working majority for change.” The assumption is that political polarization can be overcome either by (in Romney’s case) managerial expertise or (in Obama’s case) moral suasion and lofty idealism.