President Bush has announced that a top priority for his second term is reaching an immigration agreement with Mexico. And a deal with the United Sates on migrant workers is the central plank in the foreign policy of Mexico's president, Vicente Fox. But even though both sides say they want an agreement, actually getting one may be difficult.

Mexico and the United States were close to an immigration agreement early in Mr. Bush's first term, but talks stopped after the September 11 attacks in New York and Washington. The once close relationship between the two presidents cooled after Mexico pointedly refused to support the war against Iraq. Now both sides are interested in resuming talks on an agreement, but new obstacles have surfaced.

Shortly after the terrorist attacks, the United States began strengthening its border with Mexico. The increased security measures were intended to prevent terrorists from using the border to get into the United States, but they have also made it more difficult for Mexican workers to cross the border illegally. As a result, many Mexicans who are in the United States illegally are unwilling to risk going back home because they fear they might not make it back into the United States.

Francisco Gil Diaz

In an interview with VOA, Mexico's finance minister, Francisco Gil Diaz, says that any migration agreement must be flexible enough to allow movement of workers back and forth. As many as four million Mexicans are in the United States illegally, and he says the present situation is creating a population log jam north of the border. Mr. Gil Diaz says most Mexicans prefer to work in the United States for a short time and then move back home permanently, but that pattern is changing because of the tougher security measures at the border.

"What those restrictions are provoking now is that illegal migrants are staying in the U.S because of the risk of not being able to go back, and increasing the stock of people, the number of people in the States. So one of the key elements of a migration agreement would be to recognize the wish of migrant workers is really to be temporary migrants and not permanent migrants," he said.

In the United States, many opponents of illegal immigration say it denies U.S. workers jobs and places an extra burden on U.S. taxpayers because the illegal aliens use government services.

Lorenzo Meyer is a professor of political history, at the Center for International Studies at the College of Mexico. He says the illegal workers play a crucial role in the U.S. economy. "Mexico wants them to be incorporated in some kind of institutional framework, to regularize their position in the U.S. But the U.S. Congress doesn't want to do that, because it sounds like an amnesty, although they are very needed by the U.S. economy, they are not welcome because they went to the U.S. through illegal means. They crossed the border without asking permission," he said.

Whether or not the illegal Mexican workers are crucial to the U.S. economy, Mexican officials consider the money they send home crucial to the faltering Mexican economy. That is why Mexican officials want the U.S. to allow Mexican workers to move freely across the border.