Trade talk would be much more straightforward if trade agreements were only about trade, but things are never that simple. Here John McCain points out one of his non-trade reasons for supporting the Colombia FTA:
The strategic implications of rejecting this agreement are profound. Colombia is a beacon of hope in a region where the Castro brothers, Hugo Chavez, and others are actively seeking to thwart economic progress and democracy. Delaying approval of the Colombian Free Trade Agreement will not create one American job or start one American business, but it will divide us from our Colombian partners at a time when they are battling the FARC terrorists and their allied drug cartels. It will undercut America's standing with our allies in a critical region and across the world, at a moment when rebuilding these relationships has never been more important. It will set back the goal of deepening relations with our neighbors to the south and enhancing the stability, peace, and prosperity of our hemisphere.
There's a part of me that resists these considerations, preferring to focus on what makes for good economic policy. But there's another part of me that recognizes that economics is not the only consideration. I'm not sure how I come out on the issue with respect to the Colombia FTA, but I can see why people want to take these kinds of issues into account.