"President Bush is working with the Congress to reform our immigration laws, and to create a new structure that benefits immigrants who want to work, their families, and the employers who hire them," Garza said at a meeting with Texas reporters in Mexico.

"The president," Garza added, "is aware of the concerns of critics who would like to build a wall around the United States. As the former governor of Texas, he knows that such proposals are both unrealistic and undesirable."

Last week Rep. Duncan Hunter, R-Calif., introduced legislation calling for the construction, from the Pacific coast to the Gulf of Mexico, of a doublewalled high-tech security fence outfitted with lights and sensors.

Hunter is the Republican chairman of the House Armed Services Committee. Although there is no official price tag for the cost of the proposed wall, unofficial estimates range from US2 billion to US8 billion.

The Republican Party is split over how to deal with illegal immigration. One camp calls for aggressive deportations or sealing off the southern border with Mexico, while another wants to adopt guest-worker legislation to match foreign workers to employers and supply them with legal visas.

Since taking office in 2001, Bush has said he would favor a guest-worker program. He joined President Vicente Fox in declaring that the United States and Mexico are mutually dependent on immigrant labor.

Garza, a friend of Bush and a Mexican-American from Texas, echoed that sentiment.

"Looking at the big picture," he said, "I believe we should, rather than retrenching into the isolationism that tempts some, build upon our relationships with our Latin American neighbors."

An attorney and former Texas railroad commissioner, Garza said the United States shares "common goals" with Mexico and the rest of Latin America, including the reduction of poverty, "the obvious need to fight terrorism" and the promotion of free trade.