Port-of-Spain, Trinidad ? Trading their warmest words in a half-century, the United States and Cuba pressed ahead Friday with a dizzying series of gestures as leaders of the Americas gathered for a summit. The momentum was so great that the head of the Organization of American States said he’ll ask his group to invite Cuba back after 47 years.

In a diplomatic exchange of the kind that normally takes months or years, President Barack Obama this week dropped restrictions on travel and remittances to Cuba, then challenged his Cuban counterpart Raul Castro to reciprocate.

Within hours, Castro responded with Cuba’s most open offer for talks since the Eisenhower administration, saying he’s ready to discuss “human rights, freedom of the press, political prisoners — everything.” Cuban officials have historically bristled at discussing human rights or political prisoners, of whom they hold about 200.

The United States fired back Friday, with Secretary of State Hillary Rodham Clinton offering: “We welcome his comments, the overture they represent and we are taking a very serious look at how we intend to respond.”

And OAS Secretary-General Jose Miguel Insulza said he would ask the 34 member nations to invite Cuba back into the fold. Analysts doubted Insulza — known for his political caution — would have done so without a nod from Washington.

“We’re going step by step,” Insulza said. He called on the group to annul the 1962 resolution that suspended Cuba because its “Marxist-Leninist” system was incompatible with OAS principles. If two-thirds of foreign ministers agree at a meeting in Honduras next month, the communist government will be reinstated.

But while White House spokesman Robert Gibbs said U.S. officials were struck by Castro’s new openness to admit change might be needed, he also said Cuba needed to start making concrete moves toward freedom.

“They are certainly free to release political prisoners. They’re certainly free to stop skimming money off the top of remittance payments. They’re free to institute greater freedom of the press,” he said aboard Air Force One as Obama flew into Trinidad.

And Castro didn’t retreat from his criticism of U.S. policy, recalling Thursday that the United States has long tried to topple the government that he and his brother Fidel have presided over for 50 years.

The U.S. severed all diplomatic ties with Cuba on Jan. 3, 1961, just three months before exiles launched their disastrous invasion of the Bay of Pigs.