Nick Kristof tries to sell the US-Colombia PTA:

Critics of the free-trade pact worry that it would hurt American workers. But Colombian goods already enter the U.S. duty-free; what would change is that American exporters would get access to the Colombian market.

(Colombia is pushing hard for the pact not because of any immediate trade benefit but because its duty-free access to the U.S. must be regularly renewed. Businesses are reluctant to invest in flower farms or garment factories unless they know that they will be able to export to the U.S. for many years to come.)

So US workers shouldn’t worry because the PTA won’t increase Colombian exports, but Colombia wants the PTA because it’ll attract investments dedicated to exporting for many years? You can’t have it both ways, Mr Kristof.