Though physically absent, Cuba cast a big shadow over this Caribbean port at a summit of 30 Western Hemisphere leaders that ended Sunday.
Leftist Latin American leaders repeatedly harangued the United States for continuing to insist that the communist-run nation be barred from the 18-year-old Summit of the Americas circuit.
Venezuela, Bolivia and Nicaragua were unequivocal: They won't come to the next summit, set for Panama in 2015, if Cuba can't come, too.
Ecuador's president, Rafael Correa, boycotted this summit over the issue.
"There is no declaration because there is no consensus," Colombian President Juan Manuel Santos announced at the closing news conference. He said he hoped that Cuba will attend the next one.
The United States and Canada were alone in opposing Cuban participation, and they also refused to endorse in a final declaration on Argentina's claim to the British-held Falkland Islands.
President Evo Morales of Bolivia said the United States was acting "like a dictatorship."
But Sunday's outcome doesn't necessarily mean the Sixth Summit of the Americas was the last.
"We have four more years to incorporate Cuba," said Argentina's foreign minister, Hector Timerman.
His Brazilian counterpart, Antonio Patriota, said such summits are "valuable opportunities that should be repeated."
Nearly all the leaders left Cartagena quickly Sunday, allowing U.S. President Barack Obama and his Colombian host to get down to some business of their own.
They announced implementation next month of a free trade agreement that Obama said would increase U.S. imports by $1 billion a year and that Santos said would create 500,000 jobs. U.S. and Colombian labor leaders contend the accord lacks adequate mechanisms to halt killings that make this Andean nation the world's most dangerous for trade union activists.
As another sign of strengthening ties, Obama and Santos said Colombians would now be able to obtain visas to the United States that will be valid for 10 years, doubling the previous limit.
In addition to Correa, President Daniel Ortega of Nicaragua also sat out the weekend meeting, though he offered no explanation. Venezuela's cancer-stricken President Hugo Chavez also was absent. He flew Saturday night to Cuba, where he has been undergoing radiation therapy.
The United States has a half-century-old economic embargo on Cuba and says the island doesn't meet the summit's democratic standards.
Nevertheless, Obama said Sunday that he was "hopeful" for a transition, mentioning changes he'd made in U.S.-Cuba policy such as allowing U.S.-based relatives to travel there and to send money.
"I am not someone who brings to the table a lot of baggage from the past and I want to look at this problem in a new and different way," said Obama, who at the 2009 Americas summit in Trinidad declared the U.S. a partner among equals in the region.
U.S. commercial and political influence in the region has been in decline as China gains on the U.S. as a top trading partner, and many analysts say these summits are unwieldy and only make sense if there is serious follow-up on substantive issues.
"The label `Americas' doesn't seem to mean that much anymore unless you're a cartographer," said analyst Adam Isacson of the Washington Office on Latin America.
A splintering of old alliances due to region and ideology has cost the OAS clout and, many analysts say, relevance. The main alternative summits, such as the Latin America-Caribbean group and the IberoAmerican session, exclude both the United States and Canada.
The first Summit of the Americas was hosted in Miami in 1994 by U.S. President Bill Clinton. At subsequent summits, U.S. attempts to create a hemispheric free-trade zone collapsed. South America's rising left further eroded U.S. influence.
At this weekend's summit, Obama was criticized by some leaders for refusing to abandon a drug war that has claimed tens of thousands of lives and undermined governments, although he didn't shy from listening to arguments on the other side.
Santos was among leaders urging a discussion of legalization, citing the irony of Colombia's successes: While it extradites hundreds of alleged drug traffickers for trial to the U.S., criminals turn to other countries where law enforcement is weaker. Central America and Mexico, in particular, are bleeding as traffickers shift to countries of lesser resistance.
Obama said Sunday that he understood why drug violence-ravaged countries might push for decriminalizing drugs, as Guatemala did at the summit.
Such countries "have fewer resources and are starting to feel overwhelmed," he said.
Obama commented for the first time Sunday on a scandal involving prostitutes and heavy drinking that prompted the U.S. Secret Service to send 11 agents home a day before his arrival in Cartagena and to place them on leave for misconduct pending an investigation.
If it turns out that some of the allegations made in news reports are true, "of course I'll be angry," Obama said.
"We are representing the people of the United States, and when we travel to another country, I expect us to observe the highest standards," he said.
U.S. Rep. Peter King has told The Associated Press that "close to" all 11 agent had taken women to their rooms at a hotel a few blocks from where Obama later stayed.
King said the women were "presumed to be prostitutes" but investigators were interviewing the agents.
Three waiters at the hotel told the AP that about a dozen U.S. government workers they presumed were the Secret Service agents had spent a week drinking heavily, including bringing tequila and Budweiser into the hotel against its regulations.
One said he witnessed their apparent supervisor line them up and scold them on the hotel's back terrace.
Immediately thereafter, the men packed their bags and left, said the waiter, who spoke on condition of anonymity because, like his colleagues, he feared for his job.
Associated Press writer Marco Sibaja contributed to this report