Mexican President Vicente Fox said Wednesday that immigration is the most pressing challenge to the relationship between his country and the United States, but it also is their greatest opportunity.

Building a wall on the border is not the answer to illegal immigration into the United States, he said on his second day of a four-day visit to the western U.S.

"One cannot underestimate the importance of this moment and how complex this issue is for our two nations," Fox told a special session of the Utah Legislature. "Since the beginning of my administration, the government of Mexico has promoted the establishment of a new system that regulates the movement of people across our border in a manner which is legal, safe and orderly."

Fox said that policy is guided by an acknowledgment that the United States and Mexico share in the management of migration.

Fox's speech came on the same day the U.S. Senate voted overwhelmingly to limit debate on election-year immigration legislation. That cleared the way for final passage later this week of a bill that calls for tougher border security as well as an eventual chance at citizenship for millions of men and women in this country illegally.

Fox, speaking in English, said his nation must expand its economic growth so it is not necessary for people to seek work and benefits across the border, and said democracy cannot flourish unless there is economic freedom to support it.

"Until recently, Mexico was trapped in a vicious cycle of economic crisis, recurring crisis. But we have set out to change that," he said. "Today, Mexico has the soundest, safest, most stable economy of our lifetime."

He said 25 million impoverished Mexicans now have access to health, educational and nutritional support and his administration has spent more on improving the lives of its residents than any other Mexican administration.

Several dozen protesters gathered outside the state Capitol, waving American flags and carrying signs attacking proposals to offer illegal immigrants amnesty. The Minuteman Project, which opposes illegal immigration, organized the demonstration.

Salt Lake City resident Randy Maw held two signs that drew connections between illegal immigration and the struggle to fund Medicaid.

"We're overpopulated. There are too many illegals working here," Maw said.

From Utah, Fox heads to Washington state where he will meet with farmers in the Yakima Valley before moving on to Seattle. From there, he is expected to address California lawmakers and meet with Gov. Arnold Schwarzenegger and Los Angeles Mayor Antonio Villaraigosa.