President Bush announced this morning that he is sending the controversial Colombia free-trade agreement to Congress to ensure a vote this year.

The free-trade agreement faces stiff union opposition because of their worry about murders and violence against union members in Colombia, and is opposed by Democratic presidential candidates Sens. Barack Obama (Ill.) and Hillary Rodham Clinton (N.Y.).

Indeed, Clinton’s chief campaign strategist, Mark Penn, was forced to resign Sunday after he met with Colombian diplomats to advise them in how to push the agreement. That political kerfuffle may add to the pact’s problems.

The business community, however, has strongly endorsed the pact, first reached in November 2006 and heavily lobbied by the Bush administration, which argues that American exporters would benefit from the elimination of stiff tariffs. Most Colombian goods already enter the United States duty-free.