Of course none of this would be happening if the Colombian free trade agreement had been ratified in 2008. But Democrats have been instructed by their union supporters that FTAs are off limits.
If this argument were valid, then it would mean no FTAs could be advanced under the Obama administration. Oh wait, it already did push for one, and some unions supported it! It is true that union leaders in the U.S. are not particularly happy that their Colombian counterparts so often end up dead, but bashing unions is a simplistic and sometimes fact-free enterprise. So, oddly enough, the unions are blamed for the fact that three Republican senators are intentionally holding up the ATPDEA.