US President George W. Bush wrapped up a five-nation Latin America tour Wednesday that has increased pressure on him to make changes to US immigration policy.

In a region where he suffers from a lack of popularity and there is a sense of US neglect, Bush tried hard to soften his image.

He mingled with farmers in Guatemala, danced with Brazilian teenagers in Sao Paulo and toured the Mayan ruins of Mexico, the type of sightseeing he has largely steered clear of in previous foreign travel.

But he was dogged along the way by mocking "Gringo go home" rhetoric from Venezuelan President Hugo Chavez, while street protests at some of his stops showed the depth of the region's frustration with him.

In Mexico City, hundreds of demonstrators carrying signs bearing slogans like "Bush, Assassin, we don't want you as a neighbor" protested Bush's visit on Tuesday by throwing rocks at heavily armored riot police guarding the US Embassy.

Police tossed rocks back from behind a security fence, then charged at the rioters, dispersing them with tear gas. A handful of police were injured and three protesters were arrested, a police spokesman said.

Leaders of Mexico, Guatemala and Colombia all pressed Bush to work to relax US immigration policy and find a way to achieve a legal work status for the 12 million illegal immigrants in the United States.

It was a topic in talks again Wednesday between Bush and Mexican President Felipe Calderon, who delivered a blunt message on Tuesday, complaining directly about US plans to build a fence along part of the porous US-Mexican border.

As long as the United States is rich in capital and Mexico rich in labor, "migration might not be stopped, and certainly not by decree," said Calderon.

Calderon took over in December from Vicente Fox, who failed to get an immigration deal with Bush during his term.

Bush is pledging to push the Democratic-led US Congress to complete action on immigration this year with significant steps taken by August, before the campaign for the 2008 race to succeed him completely takes over.

Back home, the problems continued to pile up.

The revelation of close White House involvement in the firing of eight federal prosecutors sent White House aides into full damage control mode on Tuesday.

This came on top of revelations of shoddy outpatient care at Walter Reed Medical Center, an affair that has resulted in top-level Army resignations; the conviction on perjury and obstruction charges of Vice-President Dick Cheney's former chief of staff, I. Lewis "Scooter" Libby, and the FBI's acknowledgment that it broke the law to ferret out personal information about Americans.

Fred Greenstein, professor emeritus of politics at Princeton University, offered one explanation for why Bush was finding trouble at every turn: "When you're down, you're a target. It's the blood-in-the-water phenomena. The story becomes the shortcomings of the administration. I know that has happened in other presidencies. Things that might have been passed off suddenly become very important."

(China Daily via agencies March 15, 2007)