Throughout the Bush administration the primary public rationale for a U.S.-Colombia free trade agreement was security. This reached absurd extremes, as in 2008 when President Bush said that without the FTA, we would all lose to the FARC and Hugo Chávez would "win" (whatever that meant).
This argument does keep popping up from time to time, but it has lost its luster as its apocalyptic visions have never come to pass. So supporters are now looking to find another apocalypse. The answer: China! From the Financial Times:
China has meanwhile risen to become Colombia’s second biggest trade partner after the US, and by some estimates will overtake the US in the next decade if the trade deal is not approved.
I've been doing my best to debunk the breathless China threat meme, which is now coming fast and furious, but it has everything: foreigners we don't really understand, questionable statistics, and scenarios of "losing."
I just keep coming back to the same point: FTA supporters should argue its concrete merits rather than playing on fear.