MANCHESTER, New Hampshire (Reuters) - Republican presidential candidate Rick Perry said on Saturday he would get the U.S. military involved in Mexico's war with drug cartels, in comments likely to upset the Mexican government.

The remarks appear to be a new misstatement on foreign policy by Perry, the Texas governor who is struggling to hold on to the mantle of frontrunner for the Republican nomination.

Perry said that as president he would work with Mexico in the same way that the United States has worked with Colombia to combat drug cartels.

"The way that we were able to stop the drug cartels in Colombia was with a coordinated effort," he said in a campaign speech in New Hampshire. "It may take our military" working with the Mexican government to win Mexico's drug war, he said.

The U.S. military has advisers in Colombia who are involved mainly in training, logistical support and intelligence backup for the Colombian armed forces as they fight cocaine traffickers and leftist guerrillas.

But there are no U.S. armed forces in Mexico fighting the drug war and Mexico strongly opposes any U.S. military involvement in its territory, although it has received more than $1 billion in U.S. aid to take on the cartels.

More than 42,000 people have been killed in Mexico's drug feuds since President Felipe Calderon took office in 2006.

Perry, one of two main Republican contenders to take on President Barack Obama in the 2012 election, has stumbled before on foreign issues. He gave a rambling answer during a debate between candidates last month to a question about what he would do as president if the Taliban got hold of nuclear weapons.

(Reporting by Jason McLure, editing by Alistair Bell and Bill Trott)

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