U.S. President George W. Bush, right, and Mexican President Felipe Calderon talk during an arrival ceremony at Hacienda Temozon in Temozon Sur, Mexico, on Tuesday.

MERIDA, Mexico — President Bush's trip to sunny Latin America was no day at the beach. He was buffeted by complaints about immigration laws, ethanol tariffs, the Iraq war and accusations that the United States was ignoring its southern neighbors.

And 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 — from afar.

Instead of following their scripted plan of celebrating a shoring up of diplomatic ties with Mexico, White House aides found themselves backing and filling on why the prosecutors were axed.

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.

Democratic presidential hopefuls demanded the resignation of Attorney General Alberto Gonzales.

Sen. Barack Obama, D-Ill., said Americans "deserve to know who in the White House is pulling the strings at the Department of Justice, and why." Said former North Carolina Sen. John Edwards: "Attorney General Gonzales should certainly resign now."

"The buck should stop somewhere," Sen. Hillary Rodham Clinton said in an interview being aired today on ABC's "Good Morning America."

Gonzales accepted the resignation of his top aide and responsibility. "I acknowledge that mistakes were made here," he said, echoing the classic phrase from the Watergate era. On a round of television appearances today, Gonzales defended himself against the escalating political furor and said he had done a good job in the country's top law enforcement job. But, he added, it was up to Bush whether he remains in the administration. "I work for the American people and serve at the pleasure of the president," Gonzales said.

White House officials said the president still had full confidence in Gonzales.

As to all those Democratic calls for Gonzales' resignation, "I imagine before the day is out, every presidential candidate will call for his resignation," White House counselor Dan Bartlett said. "But the bottom line is the facts speak for themselves. The reason why these U.S. attorneys were removed were for good reasons."

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."

But the larger, overarching context is the war in Iraq and public discontent with it, Greenstein said. So missteps in other areas "look like the same story: This is a guy who's not up to the job. The administration has managed to be globally unpopular. Iraq is the great connecting tissue that does pull all the dots together."

Nobody disputes the president's ability to fire federal prosecutors — they're political appointees.

I is common for the new president to fire all the sitting U.S. attorneys, as Ronald Reagan did in 1981 and Bill Clinton in 1993. By contrast, Bush allowed some to stay on the job for several months when he took office in 2001, although all were replaced eventually.