Relatives of three U.S. contractors kidnapped by Colombian rebels more than four years ago turned Wednesday to Venezuelan President Hugo Chavez for help securing their loves ones' release under a swap of imprisoned rebels for hostages.

"We're very hopeful. They are working hard to include the three Americans" in the possible exchange, Lynn Stansell, whose son Keith is among the hostages, said after a meeting with Venezuela's ambassador to Washington, Bernardo Alvarez Herrera.

Her son was grabbed in 2003 by the Revolutionary Armed Forces of Colombia, or FARC, along with fellow U.S. contractors Marc Gonsalves and Thomas Howes when their plane crashed during an anti-drug mission.

"This is the most hopeful event we have had in 4 1/2 years," Stansell added. "We've not seen or communicated with our son in that time."

The meeting with the ambassador was spurred by last week's efforts by Chavez to help broker an exchange between the Colombian government and FARC, which holds dozens of high-profile hostages including Colombian former presidential candidate Ingrid Betancourt. The Colombian government holds hundreds of imprisoned rebels.

A definitive list of which hostages would be included in a swap has yet to be determined. Chavez has said he hopes to meet with FARC leader Manuel Marulanda, known as "Sure Shot," to hammer out such details.

Stansell's husband, Gene, said he was heartened by last week's meeting between Chavez and Colombian President Alvaro Uribe, who approved his Venezuelan counterpart's offer to try to broker a swap.

"We feel this is one of the best opportunities to arrange a kind of a diplomatic solution to this drama," said Gene Stansell. He said the U.S. government, which lists the FARC as a terrorist organization, was unwilling to consider talks with the rebels. The United States has a standing policy not to negotiate over hostages.

During his son's 54 months in captivity, "we had no proof of life ... and it does look now that there is a good chance that (with Chavez's help) something can come out of this," he said.

U.S. State Department spokesman Tom Casey said Wednesday that Washington is working with the Colombian government to try to secure the hostages' freedom, and he was not aware of what Chavez's role would be in helping arrange a swap.

"We continue to be concerned, certainly, about the three Americans who remain captive by the FARC," Casey said. "We continue to hold the FARC responsible for the conditions that they are held in, as well as responsible for their safety."

Ambassador Alvarez Herrera told The Associated Press that the families have expressed interest in traveling to Venezuela to meet with Chavez, and they "have lots of hope that they will be helped."

"If the occasion arises I will go there," Gene Stansell said. "I would even change places with my son to get him out of the FARC."