CANCUN, Mexico - President Bush and the leaders of Canada and Mexico worked to iron out disagreements over trade and border security Thursday and to keep a North American economic edge against competition from rising powers like China.

The three leaders, dressed casually in open-collared shirts, strolled together among the ancient Mayan ruins at Chichen Itza before sitting down for more intense one-on-one meetings at a beachfront resort hotel. Mexican President Vicente Fox planned a lavish dinner for his guests.

The trilateral meeting was expected to be Fox's last since he is set to leave office this year because of term limits. Bush lauded Fox for stabilizing the Mexican economy and improving the net worth of his people.

“That's important for the American economy as well,” Bush said. “The more net worth there is in Mexico, the more likely it is the Mexican may be wanting to buy a U.S. product. And vice versa, by the way.”

Bush and Fox suggested one item at the top of their agenda is now out of their hands. The U.S. Senate is debating changes to U.S. immigration laws that could affect an estimated 6 million Mexicans living illegally in the United States.

“I told the president there is a legislative process that's going forward,” Bush told reporters at the end of their private meeting. “And it may look cumbersome to some, but that's how our democracy works.”

Bush added, “I'm optimistic that we can get a bill done.”