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. He said his country believes it will take more than enforcement to solve the challenges posed by illegal immigration.

"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'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.

After his appearance in Utah, Fox planned to visit Washington state to 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.

Washington Gov. Chris Gregoire specifically pressed Fox to visit Eastern Washington, where thousands of Hispanic workers — many of them illegal immigrants — labor in the agriculture industry and comprise up to 90 percent of the population in some communities. Some Washington farmers are worried that a border crackdown could create a shortage of workers.

Fox, speaking in English, told the Utah lawmakers 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.

Fox said investing in education is vital to developing a robust Mexican economy that residents don't want to leave, and noted that about 1 million Mexican students are offered scholarships.

"I am absolutely convinced that those 1 million young (people) would have been trying to get to the United States to look for a job," he said.

"We must continue to expand economic and social opportunities, jobs and income to people so migration becomes a decision and not a necessity," Fox said, speaking in English, to the Legislature.

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.