Presumptive Republican presidential candidate Sen. John McCain (R-AZ) speaks at the 25th annual conference of National Association of Latino Elected and Appointed Officials (NALEO) in Washington on June 28, 2008. (UPI Photo/Alexis C. Glenn)

MEXICO CITY, July 5 (UPI) -- Presumptive Republican U.S. presidential nominee John McCain told Mexican leaders security at the border is a precondition of immigration reform.

McCain ended a visit to Colombia and Mexico Thursday, The Arizona Republic reported.

"I believe we must have comprehensive immigration reform. The American people want our borders secured first," McCain said at a Mexico City news conference. "That will require some walls. It will require virtual fences. It will require high-technology equipment. We must secure our borders, and then we will address the issue of comprehensive immigration reform."

McCain was one of the authors of an immigration reform bill that failed to get any traction in Congress, and caused him to lose support among illegal immigration hard-liners. Since then, he has toughened his stance on the issue.

McCain, accompanied by his wife, Cindy, and former Florida Gov. Jeb Bush, also visited the Basilica of Our Lady of Guadalupe, the most important Catholic shrine in Mexico.