President Bush, preparing for a summit with Mexican President Vicente Fox, acknowledged Tuesday he will have "a lot of selling to do" to convince the Congress that comprehensive immigration reform with Mexico is needed.

While characterizing the issue as enormously complex, Bush said he hoped an agreement could be reached on a reform program faster than the four- to six- year period suggested by Fox.

He told a group of reporters that Fox's timetable seemed realistic but added, "I hope we can do it sooner."

Bush said: "I think he is very realistic on how the United States operates. ... I do want to say I hope we come up with a solution that Congress is comfortable with, we're comfortable with and Mexico is comfortable with."

Fox, who will meet with Bush on Wednesday, is the first foreign leader to make a state visit here since Bush took office.

Bush seemed intent on enabling Fox to go back home and proclaim the visit a success.

"We're going to sign a document, there'll be a statement, there will be all kinds of different subjects that will be covered. You'll be able to hold it up and read it and he (Fox) will be able to go back and tout a unique relationship," Bush said.

Bush also made clear the importance he attaches to Mexico in his overall foreign policy.

"My foreign policy begins with this simple proposition, but a profound one: The best foreign policy means you've got to have a good neighborhood, starts with your own neighborhood," he said. "And Mexico is our neighbor. And like any good neighbor, we want Mexico, our neighbor, to do well."

At the State Department, Cabinet level officials and their subordinates from both countries discussed a range of cross-border issues Tuesday in advance of Bush's encounter with Fox.

On immigration, Secretary of State Colin Powell said he was "enormously pleased with the progress we have made on this very difficult issue."

By suggesting that an agreement could take four to six years, Fox seemed to be acknowledging the conflicting pressures on Bush from the Congress on the issue. Mexican Foreign Secretary Jorge Castaneda, who joined Powell at the State Department, said four to six years was an "ambitious goal," given that the issue dates back more than 100 years.

The most controversial issue for Bush centers on legalizing some of the estimated 3 million Mexicans who reside illegally in the United States. Many in Congress are extremely reluctant to confer legal status on migrants who arrived in the United States illegally.

One of the most outspoken critics of any such reform is Sen. Phil Gramm, R-Texas, who announced Tuesday he will not be a candidate for re-election next year. Gramm has said he would consent to legalizing undocumented aliens "over my dead political body."

It will be much easier for the Congress to accept a guest worker program that allows large numbers of Mexicans to come to the United States from Mexico to work on temporarily without fear of harassment.

Speaking to reporters before a meeting with Senate Minority Leader Trent Lott, R-Miss., Bush said he has told Fox that his goal is to make it easier for employers and prospective Mexican employees to come together.

He did not specify whether he was talking about Mexicans in Mexico or undocumented Mexicans in the United States.

"We'll look at a guest worker program that will benefit America, as well as benefit the Mexicans," Bush said.

Asked what the United States could do to most help Mexico's sputtering economy, Bush replied, "Get our own going."

Fox had promised growth rates of 7 percent a year but those projections have been revised downward sharply, partly the result of a slowing of U.S. growth.

During Tuesday's discussions at the State Department, Powell said progress was also made on cross-border cooperation on food and border safety and housing and law enforcement.

The food safety agreement involves the sharing of information by the two countries on the production of meat and produce and coordinating investigations of food poisonings.

"This agreement marks a very important new era in the food safety efforts of both our countries," said Health and Human Services Secretary Tommy Thompson.