Havana (CNN) -- The U.S. government is applying new pressure on Cuba to release an American contractor, who officials say suffers from chronic health problems.
One of the largest congressional delegations to the island in recent memory arrived in Havana on Monday with hopes of freeing Alan Gross.
Gross is serving a 15-year jail sentence for bringing banned satellite communications equipment into Cuba as part of a State Department program to spread democracy.
Gross, who has been held since 2009, said he was working to connect Cuba's small Jewish community to the Internet. But Cuban authorities said he had imported sensitive equipment to destabilize the government.
Gross is battling chronic health problems, according to his lawyers, family and the State Department. The Cuban government has disputed reports that his health is compromised.
The U.S. delegation was led by Patrick Leahy, chairman of the Senate Judiciary Committee. He was accompanied by fellow senators Sherrod Brown, Sheldon Whitehouse, and Debbie Stabenow, all Democrats, and Jeff Flake, a Republican. Democratic Reps Jim McGovern and Chris Van Hollen also made the trip.
"Nothing would give me greater pleasure than when we leave in a couple of days to have Alan on the plane with me," Leahy said.
Leahy traveled to Cuba last year with a similar delegation to press for Gross's release.
At that time, the group met with him in a military hospital where he is being held, and also met with Cuban president Raul Castro.
Cuban officials have not publicly commented on the arrival of the new delegation. But previously they have argued for the United States to lift a long-standing trade embargo, remove Cuba from a list of states that finance terrorism, and release five Cuban intelligence agents.
The State Department has rejected the notion of any prisoner swap and has said Havana cannot expect changes in U.S. policy until Gross is freed.
"We need a more mature policy toward Cuba," McGovern told reporters at the U.S. diplomatic mission in Havana. "The wall that separates our nations needs to be torn down."
The delegation plans to travel to Haiti on Wednesday.