Venezuelan President Hugo Chavez and a Colombian Marxist guerrilla commander were upbeat on Thursday (November 8) after initial talks to negotiate the release of rebel hostages, including three American men and a French woman. "Today I'm more optimistic than ever over this humanitarian exchange issue," said Chavez, dressed in military uniform with commander Ivan Marquez of the Revolutionary Armed Forces of Colombia (FARC) at his side in the presidential palace. Marquez expressed confidence Chavez's mediation could break an impasse. "Commander Manuel Marulanda Velez has given a clear order to those in charge of the prisoners of war so that they can send their respective commanders the respective proofs of life as soon as possible-- be that of Ingrid Betancourt or of the three U.S. citizens and of all who we can so that we can get them to President Hugo Chavez and Senator Piedad Cordoba," he said. The leftist pedigree of an ex-soldier who led a failed coup in 1992 gives Chavez credibility with Latin America's oldest insurgent group, the Revolutionary Armed Forces of Colombia. But it is unclear if the talks he began this week can overcome persistent obstacles, such as the Colombian government's refusal to grant the rebels a demilitarized zone. The FARC wants rebel prisoners freed in exchange for their most high-profile captives, including French-Colombian politician Ingrid Betancourt and three U.S. contract workers held for years in jungle camps. "I think that yes, an important door was opened -- a door that is very serious, very serene, very responsible, with many possibilities. It is the first time that we're talking with much seriousness and that's what I said this morning to the French representative about everyone's proofs of life -- not just of the gringos and of Ingrid (Betancourt) who is Colombian-French, but also of the Colombians who are held hostage," said Colombia Senator Piedad Cordoba. Chavez said the guerrillas pledged to provide proof the hostages are alive, something diplomats say is a key first step to making progress in talks.