MERIDA, Mexico -- In the final stop of his five-nation Latin American tour, President George W. Bush on Tuesday worked to soothe strained ties with Mexico by promising to prod Congress to overhaul tough U.S. immigration policies.

"I will work with Congress, members of both political parties, to pass immigration law that will enable us to respect the rule of law -- and at the same time, respect humanity," Bush said in a news conference with Mexican President Felipe Calderon.

Bush, facing a huge fight within his own party for his immigration plan, called it an important but sensitive issue.

"I say important because a good migration law will help both economies and will help the security of both countries," Bush said. "If people can come into our country, for example, on a temporary basis to work, doing jobs Americans aren't doing, they won't have to sneak across the border."

But Mexican President Felipe Calderon criticized U.S. plans for a 700-mile border fence, which he has likened to the Berlin Wall.

"I would like to highlight the firm political will of both governments in order to reach solutions which satisfy our needs on both sides of the border," Calderon said in a toast to Bush at a dinner Tuesday night. "In a world where everyone is competing in these frameworks of economy and policies, we know well that we can face these challenges together.

"We share problems, and solutions must be shared, also," Calerdon said. "We cannot have a North America which is safer if we do not thrust its prosperity at the same time. Mr. President, I'm happy to see that you said today that it was essential that your Congress can approve reforms in migration that you are thrusting."

Bush said the United States will not grant amnesty to illegal immigrants, but at the same time, it's not possible to deport everyone who's in the country illegally. He supports a guest worker plan that would give some illegals a shot at becoming American citizens.

"Our nations share a 2,000-mile border, and that should be a source of unity, not division," Bush said. "So we're working together to keep both sides of the border open to tourism and trade, and closed to criminals and drug dealers and smugglers and terrorists and gun runners.

"I know our country must have comprehensive immigration reform," Bush said. "We are a rule of law. But it's important for the American citizens to understand that family values do not stop at the Rio Grande River, and that it's in our nation's interests to have a comprehensive immigration law, so we can uphold the great values of America, values based on human dignity and the worth of each individual."

Calderon also criticized Bush over the thorny drug issue, saying the American president must do more to curb American drug appetites.

"We've got work to do on our side of the border," Bush said. "People provide drugs because there is a demand for drugs. And the United States must do a better job of reducing the demand for drugs.

"And at the same time, I look forward to close cooperation," Bush said. "We'll work with [President Calderon] and other presidents in our region to interdict the supply of drugs."

Protests Continue

Like everywhere else on his trip, Bush's arrival was preceded by protests.

In Mexico City, several hundred protesters burned American flags and waved banners with anti-Bush slogans. About 30 masked protesters attacked riot police at the U.S. Embassy with sticks, metal bars and blow torches. Officers responded with tear gas, pepper spray and baton charges. Several protesters have been arrested or injured.

Also Tuesday, about 100 demonstrators marched to the hotel where Bush has been staying in the city of Merida.

They attempted to bring down high metal security barriers surrounding the hotel and hurled chunks of concrete over the wall at riot police standing on the other side. Bush wasn't there at the time.

Another 30 protesters ran through Merida's town square, smashing windows at the town hall and spraying graffiti on the walls.