Mexican President Vicente Fox (search) said President Bush had called to brief him Wednesday on his proposed immigration proposal. Fox indicated the plan was "very interesting" but said he had to wait to hear details before responding formally.

Fox, whose country has roughly 10 million citizens working in the United States, called the issue "the fundamental theme of the bilateral relationship" between the two countries and noted he had been discussing the issue with Bush since before the two took office.

Fox said the proposal Bush outlined to him would recognize "the value of these Mexicans who find themselves working there in the United States" by trying to give all of them "all the rights that any worker has in that country, although they are not American nationals or do not have documents at this moment."

Fox, who was making a speech on education, said the plan would let the migrants come and go to Mexico, something that is now dangerous and difficult for undocumented workers (search).

"So it is a very interesting program," he said. "We are going to wait for details."

Earlier in the day, Mexico's ambassador to Washington praised the renewed U.S. interest in immigration reform.

"The government of Mexico gives the clearest welcome to this renewed interest by the United States to deal with the topic of immigration," Ambassador Juan Jose Bremer told reporters during a meeting of diplomats at Mexico's Foreign Relations Department.

"I think that Sept. 11 set back the advance of the topic of immigration. Now we have perceived movement."

Bremer said he would have to wait for Bush's speech later Wednesday to make more detailed comments.

Fox has repeatedly urged Bush to legalize the millions of Mexicans who work in the United States illegally. The money they send home is Mexico's second-largest source of foreign income, behind oil.

Asked about criticism here that the measure may not be as broad as Mexico had hoped, Bremer said that "there has to be a progressive, step by step strategy."

He said Mexico sought "concrete, progressive advances for our people."

U.S. officials say Bush's proposal would provide a way for illegal immigrants who can show they have employment to work legally, although temporarily, in the United States.

The new "temporary worker program" (search) also would include people still in their native countries who have a job lined up in the United States.