President Obama concluded a contentious hemispheric summit on the defensive Sunday as it ended without agreement on whether Cuba’s Communist leaders should be invited to the next meeting, something the United States firmly opposes.

The standoff meant that the sixth Summit of the Americas ended without an official declaration — a negotiated statement of shared principles from the hemisphere’s heads of state — and left open the question of whether there would be a seventh such meeting.

The ambiguous conclusion underscored the fact that Obama, while pledging a new relationship with the United States’ leery southern neighbors, has had little success in bridging significant policy differences that have divided the region for decades.

With the scandal involving a number of Secret Service agents and prostitution coloring the weekend meeting, Obama departed here with the U.S. image mildly blemished and the enduring political differences between the hemisphere’s wealthy north and rising south firmly intact.

“I’m not somebody who brings to the table here a lot of baggage from the past, and I want to look at these issues in a new and fresh way,” Obama said during a Sunday news conference with Colombian President Juan Manuel Santos. “I am sometimes puzzled by the degree to which countries that themselves have undergone enormous transformations, that have known the oppression of dictatorships or have found themselves on the wrong side of the ruling elite, and have suffered for it, why we would ignore that same principle here.”

Cuba and the decades-old U.S. embargo against it, which Latin American and Caribbean leaders derisively call a “blockade,” has been a traditional bone of contention between the United States and much of the rest of the region.

But it emerged here as only one of several issues, including U.S. anti-drug and monetary policy, that together illustrated how far the United States remains outside the hemisphere’s political consensus.

The summit was more buttoned up than the previous one three years ago, largely because several of the region’s most anti-American leaders did not attend. The cultural programming around the meetings showcased this lovely seaside city and the progress made by Colombia, where an array of drug-funded armed groups has faded in recent years.

Santos attributed Colombia’s success in part to the billions of dollars in U.S. aid over the past decade. But the open criticism directed toward the U.S. approach to several issues also underscored the new confidence felt by Latin American leaders as they guide a region that is improving economically while the United States struggles to find its financial footing.

Although Obama has presented the United States as a more equal partner in hemispheric affairs and has spoken forcefully on issues such as inequality that have defined Latin American politics for years, some of his policies fall outside the region’s mainstream. He defended them staunchly, nonetheless.

Many leaders here pushed for a new strategy to combat the illicit drug trade, fueled by U.S. demand. Some proposed legalization — for possession and by regulating the trade — but Obama made clear here that he does not believe it would prove more effective than the law enforcement approach funded by the United States.

“I think it is wholly appropriate for us to discuss this issue,” Obama said, adding that while Colombia is emerging from a “wrenching period,” several “smaller countries” in Central America are “starting to feel overwhelmed” by drug violence. “It wouldn’t make sense for us not to examine what works and what doesn’t.”

New leaders emerging

As the Castro brothers in Cuba grow old, Venezuela’s Hugo Chavez battles cancer and other important regional leaders leave office, Latin America is determining which new leaders will emerge.

A tacit competition has shaped up between Brazil and Colombia, both growing economically and benefiting from a skilled business class. The summit showcased their leaders, who were sometimes at odds with Obama.

Santos and Brazil’s Dilma Rousseff, who visited the White House last week, publicly criticized U.S. monetary policy for devaluing the currencies of developing countries.

And Santos worried aloud whether America is “exporting unemployment” to Latin American countries that have weathered the global economic downturn better than the United States.

“We all have the feeling of the enormous opportunities we have to work together,” Santos said at his news conference with Obama, putting the best light on their differences.

There were moments of agreement, too. Obama announced here Sunday that Colombia has complied with a key condition of the free-trade agreement passed last year that is designed to better protect labor activists from political violence.

The labor certification allows the deal to take effect May 15. U.S. exports to Colombia last year totaled $14.8 billion, and the agreement will eliminate tariffs on 80 percent of U.S. consumer and industrial goods bound for the country and phase the rest out over the next decade.

But the election-year decision has angered U.S. labor leaders, who say Colombia has not made enough progress in protecting union activists in Colombia and in punishing those who commit crimes against them.

In a letter to Obama last week, AFL-CIO President Richard Trumka wrote that “less than 10 percent of the nearly 3,000 cases of trade unionists murders since 1986 have reached a conviction,” and that “none of the 29 labor activists killed in 2011 had their cases resolved by a successful prosecution.” The labor group endorsed Obama for president last month.

“We all know that more work needs to be done, but we have made significant progress,” Obama said of Colombia’s labor rights record.

Cuba issue still resonates

Cuba, a historic wedge issue between the United States and its closest political allies in the region, overwhelmed the summit’s final day.

Under U.S. pressure, Cuba’s Raul Castro was not invited to this meeting, and many influential regional leaders, led by Rousseff and Santos, indicated that they would not attend another without Cuba.

Ecuador’s president, Rafael Correa, declined to attend the summit in protest, and other leading leftists close to Cuba, including Nicaragua’s Daniel Ortega, did not show up.

Chavez, who usually thrives on the attention of regional forums, was also not present, because of illness.

But the issue still resonates throughout Latin America, evoking the Cold War-era political divide between left and right that Obama on Sunday said had ended.

“The fact of the matter is that Cuba, unlike the other countries participating, has not moved to democracy, is not respecting human rights,” Obama said. “I’m hoping the transition takes place.”