Santos earlier held talks with the Cuban President Raul Castro and Venezuela's Hugo Chavez in a bid to try to stop leftist countries from boycotting the regional meeting, amid controversy over whether Communist-ruled Cuba would be invited to the event. "This (extending the invitation) is an issue that requires a consensus, which unfortunately we have failed to find," Santos told reporters at Havana airport before returning to Bogota. The Summit of the Americas is an event closely linked to the Washington-based Organization of American States (OAS), a group that expelled Cuba in 1962. In February, the leftist president of Ecuador called for leftist Latin American nations belonging to the ALBA, a Venezuelan-backed regional group, boycott the Summit of the Americas if Cuba is not invited. Washington vehemently opposes inviting Cuba, and Santos -- a US ally who also has amicable relations with Havana and Caracas -- had been trying to broker a compromise. Santos first met Wednesday with Castro, 80, and then had discussions with Chavez, 57, who is in Cuba recovering from recent cancer surgery, Colombian officials said. The Summit of the Americas is currently scheduled for April 14-15 in Cartagena, Colombia. At the previous Summit of the Americas, held in Trinidad and Tobago in 2009, Cuba's expulsion was reversed, but Havana refused to rejoin the OAS. Cuban Foreign Affairs Minister Bruno Rodriguez however said in February that Cuba could go to the upcoming Summit as a "guest." In December Chavez held the first meeting of another regional group, the Community of Latin American and Caribbean States (CELAC), which excludes Canada and the United States. Chavez has said he hopes will the new group will replace the 64-year-old OAS, which critics say is slow to react and too favorable to Washington.