President Obama (left) shakes hands with Cuban President Raul Castro during the official memorial service for former South African President Nelson Mandela on Dec. 10, 2013 in Johannesburg. Will they meet again? (Chip Somodevilla/Getty Images)

For the United States, the last Summit of the Americas was a fairly regrettable experience.

That 2012 event is probably best remembered for the prostitution scandal that embarrassed the Secret Service, its agents' reputation for steely discipline wilted by the tropical heat of host city Cartagena, Colombia.

Things didn't go much better for President Obama inside the conference hall. The region's heads of state dog-piled on Washington over its Cuba policies, saying there should be no further meetings if the United States insisted on excluding Havana.

With the next summit scheduled for April 2015 in Panama, the Cuba issue is once more giving the administration some sweats.

Earlier this month, Panama's foreign minister flew to Havana to personally invite Cuban leader Raul Castro to participate, even though the island was kicked out of the Organization of American States (OAS), which sponsors the events, in 1962.

Panama's new president, Juan Carlos Varela, said at the United Nations last week that he wants all the hemisphere's heads of state to attend.

This leaves Washington, and Obama, in a bind. The United States and Canada are the only countries in the region that don't want communist-run Cuba to be there. But if Obama skips the conference, or sandbags it by sending Vice President Biden, it would render the already-weak OAS even more hobbled, and potentially deal a fatal blow to the possibility of future summits.

If Obama does attend, it could lead to some awkward shoulder-rubbing with Raul Castro. A mere handshake between the men caused a stir at Nelson Mandela's memorial. This time, Castro's presence could force Obama to defend the U.S.'s half-century-old economic sanctions against Cuba-- measures that are criticized even by U.S. allies in the region like Colombia and Mexico.

On Friday in New York, the U.S.'s top diplomat for the region, Roberta Jacobson, did not say if the president would show. She reiterated to reporters that the U.S. doesn't think Cuba deserves to attend because it lacks a commitment to democratic governance, one of the agreed-upon principles of the OAS and the summits. Fidel and Raul Castro have ruled the island since 1959.

But among Latin American leaders, even the most pro-American tend to think that the U.S. trade sanctions and efforts to isolate Havana have backfired. The summits have turned into one of the most prominent forums for Washington to hear that view, from critics and allies alike.

Held every three years or so, the events are a rare gathering of the hemisphere's heads of state. They were launched by the Clinton administration in 1994 as an attempted first step toward a hemisphere-wide free trade agreement.

That idea fizzled out long ago. Now, ironically, it's opposition to the U.S.'s Cuba policies that has become a cause of consensus among the region's leaders.

Opponents of the Castro government say Obama should attend the summit anyway, and offer a forceful defense of democratic principles in a region drifting toward strongman rule in countries like Venezuela, Ecuador, Nicaragua and Bolivia-- some of Cuba's closest allies.

But for a president who already has a full-plate of foreign policy entanglements, there may be a strong desire to steer clear of a place where he's likely to get an earful, and maybe not much else.