Vidal says that the U.S. demand that Cuba release Gross before it takes any steps to improve relations with the island is just a "pretext" not to do so.
The State Department reacted sharply, saying Vidal's statements only reinforce the U.S. belief that Gross is being held hostage and that there is no justification for his imprisonment.
There hasn't been diplomatic relations between the two countries for five decades, although ever since the Carter presidency they have maintained Interests Sections in each other capitals.
Vidal was echoing the position laid out in an official letter sent to Blitzer earlier this week saying Havana has offered to hold a "dialogue to find a humanitarian solution...on a reciprocal basis" to the case of Alan Gross, sentenced to 15 years on charges of trying to subvert the government.
That offer provoked speculation that the Cubans were holding out to swap Gross for five Cuban imprisoned in the U.S. on spying charges for nearly 14 years. Cuba says the men were only seeking information that would help prevent terrorist actions against the island and not U.S. government secrets.
The Gross family has been agitating the media to cover the story and Gross used one of his weekly calls to his family to dial in to Blitzer's show, The Situation Room. In their conversation broadcast May 4th Gross describes himself as a "hostage".
The Cubans have allowed his wife and a string of political and religious figures to visit Gross in the Havana military hospital where he is being held rather than in a common prison.