Via Brad DeLong, a David Leonhart column on how little NAFTA has to do with Ohio's economic woes. Still, I think hearing that the "more important cause of Ohio's jobs exodus is the rise of China, India and the old Soviet bloc" rather than trade with Mexico as such is going to do relatively little to cause Ohions to reverse their skepticism about trade policy. With trade as with every other policy area, most people's understanding of the details is very fuzzy.
"NAFTA" means "recent trade phenomena" and there's no denying that recent trends in international trade have caused economic dislocation in the rust belt. Still, responsible politicians wouldn't be promising to help Ohioans out by renegotiating NAFTA when renegotiating NAFTA won't actually deliver much help to the state. It's a bit of a cynical ploy -- by thundering loudly and pounding the table about the need to renegotiate the deal, you set yourself up for a situation where very minor modifications that barely impact anyone (for good or for ill) count as fulfilling the promise.