FOREIGN leaders have jostled to be in pictures with him and pressed for autographs. The Venezuelan President, Hugo Chavez, who called the last US president the "devil", gave Barack Obama a book on Latin America and clasped hands with him as if he had been reunited with an old friend.

Mr Obama proved an able statesman during his trip to Mexico and Trinidad and Tobago, which ended yesterday. But, like his trip to Europe earlier in the month, he found that a leader's charisma cannot overcome national interests or policy disputes marinated in decades of resentment.

Mr Obama came to the Summit of Americas hoping to talk about issues that invite consensus, environmental protection and economic recovery among them.

Many of his counterparts, however, wanted a commitment to end the US's 47-year trade embargo against Cuba - a commitment Mr Obama would not make.

"It's fair to say there's a disagreement on Cuba," said the deputy National Security Adviser, Denis McDonough.

The Mexican President, Felipe Calderon, also wanted the US to reinstate a ban on assault weapons, arguing that since the prohibition lapsed in 2004 the number of these powerful guns showing up in Mexico has soared. Mr Obama would not relent.

But he did make a concession on Cuba before arriving in Trinidad, lifting restrictions on Cuban Americans who wish to visit family.

The White House knew beforehand that Cuba would be a focus of the summit, aides said.

At the opening ceremony on Friday, Mr Obama said the US sought a new beginning with Cuba. "I am prepared to have my administration engage with the Cuban Government on a wide range of issues - from human rights, free speech, and democratic reform to drugs, migration and economic issues," he said.

The statement followed a comment by the Cuban President, Raul Castro, a day earlier, which expressed willingness to discuss a wide range of topics traditionally off-limits, including human rights.