The results of the survey, commissioned by the Atlantic Council, a prominent Washington research institution, and released on Tuesday, were described by the group as an unprecedented reflection of shifting American attitudes toward Cuba that confound some long-held assumptions, particularly about Cuban-American antipathy toward the government of Raúl Castro.

The results also come against a backdrop of increasing sentiment in Florida and elsewhere that the American economic and political isolation of Cuba, one of the most enduring elements of United States foreign policy, not only has failed to satisfy its purpose of unseating the Castro government but may even be helping to perpetuate it.

“This survey shows that the majority of Americans on both sides of the aisle are ready for a policy shift,” Peter Schechter and Jason Marczak, the top two executives at the Adrienne Arsht Latin America Center of the Atlantic Council, wrote in an introduction to the survey. “Most surprisingly, Floridians are even more supportive than an already supportive nation to incrementally or fully change course.”