WASHINGTON (CNN) -- Sen. John McCain, the presumptive Republican nominee for president, arrived in Tuesday in Colombia on a three-day trip that includes Mexico to talk about trade and drugs.
"What happens in Colombia and Mexico is very important to the future of America," McCain said Monday.
His free-trade stance is increasingly unpopular with Americans, according to a CNN/Opinion Research Corporation poll released Tuesday.
The survey found 51 percent of the Americans questioned view foreign trade as a threat to the economy -- the first time in a CNN poll that a majority of respondents reported holding negative views on free trade.
McCain backs the Colombia Free Trade agreement, which currently is in limbo. Congressional Democrats are blocking the deal, citing the intimidation and killing of Colombian labor activists by right-wing militias.
The Arizona senator admitted there "were human rights abuses by the paramilitaries, and these people need to be brought to justice, no matter who they are or where they are."
"But I balance that against [Colombian President Alvaro] Uribe and his administration's rescue of Colombia from a failed-state status," he said.
"You got to stand on principle. I believe in the principle of free trade," he said, adding that protectionism could make a bad economy worse.
He pointed to the example of Herbert Hoover, the Depression-era president who signed protectionist legislation into law.
"We went from a recession into one of the great depressions of our history," he said. "I've got to convince people that I have a plan to give them the kind of education and training they need."
In response to a question about President Bush, he compared his stance on trade to that of a different president.
"I'm also closely aligned with President Clinton. President Clinton is the one who signed the free trade agreement with North America," McCain told reporters on his campaign bus.
A top aide to Sen. Barack Obama, the presumptive Democratic nominee for president, said the McCain trip is actually an effort to win Latino votes at home.
"He's not doing it because he thinks the region is important, he's doing it because he wants ... to try to send a message to Latinos in the United States, to say, 'Focus on these things,' rather than on things that he doesn't have an answer for in the Latino community," said Dan Restrepo, Obama's senior adviser on Latin America.
Obama has vowed to amend the North American Free Trade Agreement if elected president.
McCain launched a Web-only advertisement touting the Colombia Free Trade Agreement Tuesday, in English with Spanish subtitles. The campaign confirmed that it was not buying any television advertising time for the spot.
"We must encourage more trade agreements to create more jobs on both sides of the border; that's why I'm behind the Colombia Free Trade Agreement," McCain says in the advertisement.