When President Bush flew to Mar Del Plata, a resort town on the Argentine coast, for the Summit of the Americas in 2005, he was met with violent protests, fire bombings in the streets and an anti-American rally some 25,000 strong. After two days of disastrous negotiations, he departed empty-handed.

While President Obama is likely to get a sunnier reception when he travels to Trinidad and Tobago this week for the fifth summit meeting, it could be his homecoming he needs to worry about. The opening up of the floor to issues such as violence along the U.S.-Mexico border and relations with Cuba means Obama will have to walk the line between Latin America's heightened expectations and domestic political considerations.

"Policy towards Latin America is very much constrained by domestic politics, whether you're talking trade or [agriculture] or immigration or Cuba policy or energy policy," said Julia Sweig, director for Latin America studies at the Council on Foreign Relations. Obama is more popular at home and in Latin America than his immediate predecessor, but he'll face a host of challenges that Presidents Clinton and Bush -- whose agenda at the summits focused mostly on expanding free trade -- did not.

Coverage of this year's summit, which is officially scheduled to focus on energy and the economy, is likely to be dominated by the only Latin American nation not represented: Cuba. Regional leaders, including Brazil's Luiz Inacio Lula da Silva, have raised calls in recent weeks for the U.S. to begin normalizing its relations with Cuba, encouraged by the administration's willingness to loosen restrictions on travel and remittances for Cuban-Americans.

Their hopes will clash, however, with those of anti-Castro Cuban-Americans, whose intensity has mellowed somewhat in recent years but who still wield considerable sway. During the debate over the economic stimulus bill in March, for example, Sens. Bill Nelson, D-Fla., and Robert Menendez, D-N.J., withheld their support until receiving personal assurances from Treasury Secretary Timothy Geithner that a provision liberalizing agricultural shipments to Cuba would not be enforced.

"I do not anticipate that the United States will have anything to say about Cuba at the summit," said Aldo M. Leiva, a director of the Cuban American National Foundation in Miami. "The United States is not going to cave in to pressure on the embargo." Leiva added that the debate over the embargo "is not for the president and his advisers, it's for the American people."

"He can't simply say we're not going to do anything, and at the same time he can't announce something there that hasn't been vetted here and hasn't been discussed with Cuban-Americans here," said Peter Hakim, president of the Inter-American Dialogue. "It would be foolish domestically for him to do so, let me put it that way."

That might explain in part why U.S. summit adviser Jeffrey Davidow downplayed the Cuba issue at a Council on Foreign Relations event last week, saying the U.S. didn't want to be "distracted" from the meeting's other goals. And why the administration chose this week to fulfill a campaign promise and roll back Bush-era restrictions on travel and communication with Cuba.

But at least some of the region's leaders will arrive in Port of Spain hoping to push Obama further. Venezuelan President Hugo Chavez has been particularly outspoken on the subject and is hosting an alternative summit this week in Caracas with other Latin American heads of state, in part to express solidarity with the Castro regime.

Even if they fail to provoke further concessions for the island nation -- which seems likely -- Obama will face a chorus of populist anti-American leaders, something his predecessors never had to deal with. Chavez's provocations in Mar Del Plata -- he excoriated Bush in front of a packed soccer stadium before going into the meetings -- went a long way toward derailing those talks. This time around, Chavez will be joined by Rafael Correa of Ecuador, Daniel Ortega of Nicaragua and possibly Evo Morales of Bolivia.

Chavez's rhetoric on Obama has been calmer than it was towards Bush, but it seems safe to say the leader who recently called Obama "a poor ignoramus" would love to force a confrontation. And, as the recent media kerfuffle over Obama's apparent bow to Saudi King Abdullah demonstrated, the president's domestic critics will be watching closely for any perceived missteps.

Obama will feel pressure from friendlier sources as well, particularly the Democratic lawmakers who will be accompanying him to the summit. Sen. Max Baucus of Montana and Reps. Sam Farr and Xavier Becerra of California, Charles Rangel and Nydia Velazquez of New York, Ciro Rodriguez of Texas and Kendrick Meek of Florida will be making the trip.

Meek, whose Miami-area district is home to a large Haitian-American constituency, said he sees the first summit to be held in the Caribbean as the ideal opportunity to push Haitian issues to the fore. That includes encouraging more international aide for the tiny country, where 80 percent of the population lives under the poverty line, and refocusing the administration's priorities on granting temporary protected status to Haitian immigrants already in the U.S.

"Haiti has to be one of the bigger discussions when the Americas come together for a summit," Meek said. "It's the poorest country in the Western Hemisphere." Hailing Secretary of State Hillary Rodham Clinton's planned stop in Port-au-Prince before she continues on to Trinidad, Meek said the secretary's visit shows that "the U.S. will not only continue to take the lead as relates to Haitian assistance, but also encourage the Americas to play a very strong role in helping Haiti recover."

"Obviously, the Obama administration has its plate full," said Rep. Alcee Hastings, another South Florida Democrat who represents a large number of Haitian-Americans. "But while its plate is full, I'm asking them to let some crumbs drop off of the plate, and grant temporary protected status to Haitians."

For all the domestic hurdles Obama will have to negotiate, he'll at least be relatively safe on one point: free trade. Past summits focused on establishing a Free Trade Area of the Americas, but those dreams are largely acknowledged to have died in Mar Del Plata.

The administration has signaled its intention to move forward with negotiations on a free trade deal with Colombia that major unions have opposed, but Obama seems unlikely to have to move beyond indicating his support in the abstract. "In terms of trade generally, the president has made it clear -- and clearly it's policy to avoid protectionism," Davidow said in a conference call with reporters this week.

"That's been off the agenda," said Hakim. "There may be a few discussions of it in the context of protectionism vis-à-vis the U.S. stimulus package, but nobody thinks trade, particularly trade agreements, are going to be much discussed."

"This is the first encounter with the region as a region," said Bernard Aronson, former assistant secretary of State for Inter-American Affairs. "And there are these issues where there are conflicting views between the domestic politics and the foreign politics. That makes it more important if Obama chooses to define where he stands."