HAVANA, Cuba (CNN) -- New Mexico Gov. Bill Richardson wrapped up a week-long trade mission to Cuba Thursday, a trip in which he also pursued another goal -- bringing about the release of a jailed U.S. contractor.

"My objective is very clear: See if I can get [Alan] Gross out, or make it easier for somebody else to do it," Richardson told CNN.

Alan Gross, an American contractor, has been held in a Havana jail since December on suspicion of spying, although no charges have been formally brought against him.

President Raul Castro said Gross was illegally distributing satellite communications equipment and has linked him to clandestine U.S. operations on the island nation.

Richardson said his visit to Cuba is primarily a trade mission intended to bolster agricultural sales, but acknowledged that the White House has asked him to press the Gross case with Cuban officials.

The New Mexico governor has often acted as an informal negotiator for U.S. administrations, engaging in high-level talks with North Korea, Sudan and Iraq.

He speaks fluent Spanish and has previously met with former Cuban President Fidel Castro, negotiating the release of three political prisoners in 1996.

Richardson would not confirm whether he planned to meet with the former Cuban leader during this visit.

He is expected to leave Havana on Friday after a series of meetings with Cuban officials, including Cuban Foreign Minister Bruno Rodriguez.

Richardson's visit coincides with an announcement Monday by the island's Roman Catholic Church that six more Cuban political prisoners would be freed soon.

The group's release would raise to 32 the number of prisoners set free since early July in a deal brokered with the church and Spain's Foreign Ministry.

The prisoners are a part of group of 75 dissidents imprisoned during a government crackdown on political opposition in March 2003.