CARTAGENA, Colombia — Sen. John McCain arrived yesterday in Colombia to promote a free-trade agreement he says would bolster a key ally in the war on drugs, but has stalled in Congress.

The presumptive Republican presidential nominee is visiting this South American country to showcase his foreign policy and pro-business credentials.

The U.S.-Colombian trade deal has become a key issue in the presidential race, generating opposition from labor unions and others who worry that lower tariffs on Colombian goods could lead to a loss of American manufacturing jobs.

The Republican presidential hopeful began a three-day visit to Colombia and Mexico after a campaign swing through Indiana and Pennsylvania, two states hit hard by the loss of manufacturing jobs partly due to trade deals such as the North American Free Trade Agreement with the U.S., Mexico and Canada, which McCain strongly supports.

McCain and his wife, Cindy, met Colombian President Alvaro Uribe at the president's ceremonial home in Cartagena before a meeting between the two men and several Colombian Cabinet ministers.

McCain conceded Monday he still has work to do to convince voters in industrial swing states in the Midwest, where the presidential election could be decided, that his support for free trade will benefit them, not just cost more jobs.

He pledged to improve programs for displaced workers and unemployment insurance if elected, but acknowledged that wouldn't be enough.

"I have to convince them the consequences of protectionism and isolationism could be damaging to their future," the Arizona senator said.