Bush, in Mexico, Pushes Secure Borders and 'Comprehensive' Immigration Bill

President Bush wrapped up his trip to Mexico on Friday, calling for more secure borders for the United States, Mexico and Canada and saying the United States needs to tackle the contentious issue of illegal immigration.

"We've got long borders. And we've got to make sure we work hard to secure the borders," Bush said at a joint news conference with Mexican President Vicente Fox and Canadian Prime Minister Stephen Harper.

The United States, Mexico and Canada need to enhance trade and tourism, but they also must prevent smugglers and terrorists from entering their countries, Bush said.

While the Senate continues to battle over immigration legislation, Bush pushed for a "comprehensive bill."

The president pledged his continued support for a guest worker program that would allow undocumented immigrants to remain in the United States and continue to work at low-paying jobs. But Bush did not say whether he would veto a bill that does not contain a guest worker program.

"We have a line of people waiting, people who were in our country legally, waiting to become a citizen. And people who have been in our country illegally should not get ahead of the line who are there legally," Bush said.

The debate in Congress follows a proposal that would give legal status to an estimated 11 million illegal immigrants in the United States and expand guest worker programs for about 400,000 immigrants each year.

The bill under debate in the Senate includes a guest-worker proposal, while the House has passed rival legislation. Bush supports the Senate proposal.

Bush also defended a new U.S. law, due to take effect Dec. 31, 2007, that requires all American and Canadian travelers to carry passports when crossing into each other's country.

Harper said he had expressed Canada's concern to Bush over the new restriction.

"Over the course of the next few months, we will be doing everything possible to ensure the security along our borders and to be able to move our merchandise back and forth," Harper said.

But, Bush said, "Congress passed the law and I intend to enforce the law." He said he believes the program, if properly implemented, "will facilitate travel and facilitate trade, not hinder travel and trade. I think we can be wise about the use of technologies."

Bush said all three countries need to work together because they face economic challenges from China and India.

"And my attitude [is] we shouldn't fear these challenges, we ought to welcome them, and position ourselves so that we can compete," Bush said.

The news conference was held in an indoor tennis court, decked out with enormous maps of North America and a white backdrop with mammoth video screens flanking the three leaders' podiums.

Earlier on Friday, Bush met with American, Mexican and Canadian chief executive officers to get feedback from the private sector on North American competitiveness in the global economy and other economic issues.

The next trilateral meeting will be held in Canada in 2007, Harper said.

FOX News' Wendell Goler and The Associated Press contributed to this report.