Climate change. Peace in Colombia. Argentina's longstanding claim of sovereignty over the Falkland Islands.

Heads of state representing lands from Tierra del Fuego to the North American tundra pressed their concerns in a marathon session at a Panama City convention center as the seventh Summit of the Americas wrapped up Saturday.

It was all overshadowed by the first substantial face-to-face encounter by sitting U.S. and Cuban leaders since 1958, as presidents Barack Obama and Raul Castro seek to restore diplomatic relations and lower the combative tone that has prevailed since ties were severed 54 years ago.

As in past summits, several of Washington's most outspoken critics used the forum as a bully pulpit to rail against U.S. behavior in the region, from current issues such as travel and financial sanctions against seven Venezuelan officials over human rights concerns to long-ago insults like 19th century expansionist policies.

Ecuador's populist president, Rafael Correa, cited the Declaration of Independence's language enshrining life, liberty and the pursuit of happiness as inalienable rights — then noted that the document's author, Thomas Jefferson, was a slave owner.

Obama sought to chart a smoother course in relations with Latin America, and many other leaders notably did not take a page from the leftist ALBA bloc nations and take strong stands against Washington.

The moderate voices included the presidents of Latin America's two most populous and economically powerful nations: Brazil's Dilma Rousseff, who only briefly criticized the U.S. sanctions on Venezuelans as "counterproductive and inefficient," and Mexico's Enrique Pena Nieto, who delivered an attack-free address.

Pena Nieto spent his allotted time expressing solidarity with Chile, whose president skipped the summit to oversee the country's response to deadly flooding in recent days; backing Colombia's peace talks with the hemisphere's largest surviving guerrilla army, a common theme on the day; and praising U.S.-Cuban detente and Castro's unprecedented attendance.

"All 35 states that make up the Americas are here. ... This historic gathering is thanks to the dialogue between two great friends of Mexico, Cuba and the United States," Pena Nieto said. "Our nation supports, recognizes and is an ally of this process."

Obama announced that Rousseff will visit Washington in June, rescheduling a 2013 trip that she called off amid a diplomatic flap over revelations that the U.S. National Security Agency had covertly monitored her private communications.

She said she was pleased by the invitation and looked forward to the trip.

A potentially tense moment was avoided when President Nicolas Maduro of Venezuela didn't follow through on a pre-summit pledge to confront Obama with 10 million signatures on a petition demanding the repeal of the sanctions. Instead, he said the petitions would be delivered through diplomatic channels.

Maduro's change of heart came after senior U.S. State Department official Tom Shannon flew to Caracas to meet with Maduro, and Obama and other officials walked back language declaring Venezuela's political and economic instability a threat to U.S. national security.

Obama and Maduro met briefly in private later in the day.

"President Obama indicated our strong support for a peaceful dialogue between the parties within Venezuela," said Bernadette Meehan, a spokeswoman for the White House's National Security Council. "He reiterated that our interest is not in threatening Venezuela, but in supporting democracy, stability and prosperity in Venezuela and the region."

Venezuelan presidential aide Teresa Maniglia said the two leaders greeted each other in Spanish, but she offered no additional details.

"There was a lot of truth, respect and cordiality" she said on her Twitter account.

Obama did not mention the encounter in remarks at the conclusion of the summit.

But during a speech at the summit, Obama defended his administration's right to criticize policies it doesn't agree with.

"When we speak out on something like human rights, it's not because we think we are perfect but it's because we think the ideal of not jailing people if they disagree with you is the right idea," he told regional leaders, without mentioning Venezuela by name.

The summit ended without a joint declaration, reflecting the ideological divisions that remain.

Nicaraguan President Daniel Ortega regretted that no consensus could be reached for "political" reasons, an apparent reference to disagreement over the U.S. sanctions on the officials in Venezuela.

Host nation Panama announced Saturday evening that Peru was selected as the seat of the next Summit of the Americas, in 2018.

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Associated Press writers Andrea Rodriguez, Juan Zamorano and Josh Lederman contributed to this report.

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Peter Orsi on Twitter: www.twitter.com/Peter_Orsi

Joshua Goodman on Twitter: www.twitter.com/APjoshgoodman