A Venezuelan businessman sitting in a Colombian jail could provide valuable evidence about the suspected close relationship between cocaine traffickers and the Venezuelan government, U.S. officials say.

But Colombia’s government has signaled that Walid Makled will not be extradited to the United States, which has blacklisted him as a “significant foreign narcotics trafficker.” He will be sent to Venezuela, they say, where President Hugo Chavez accuses him of fabricating stories as part of a smear campaign to debilitate his leftist movement, which opposes U.S. policies in the region.

If Makled is extradited to Venezuela, as Colombian President Juan Manuel Santos pledged last year, U.S. prosecutors looking into the transshipment of cocaine through Venezuela would be denied a vital witness. That has worried some in the U.S. Congress, where leading GOP lawmakers who shape Latin America policy say Colombia should reverse itself.

For the Santos administration, which receives significant U.S. assistance to fight drugs, the tug of war has been uncomfortable.

Sen. Richard G. Lugar (Ind.), the ranking Republican on the Senate foreign relations committee, said that if Makled ends up in Venezuela, U.S. counter-drug investigators “would be unable to use the information he has already provided to them to legally dismantle some of the most important drug networks in the world .”

Rep. Connie Mack (R-Fla.), chair of the House subcommittee on Western Hemisphere affairs, said the Justice and State departments had moved too slowly on requesting the extradition, leaving Santos little choice but to honor a request Venezuela made first.

“This is a national security issue,” said Mack, who has accused Venezuela of aiding drug-trafficking groups. “And I’m outraged that the Justice Department is completely inept when it came to this.”

Mack, who discussed the case last year in Bogota with the Santos administration and U.S. Embassy officials, said the Venezuelans on Aug. 26 made their request for extradition, a week after Colombian authorities arrested Makled on a warrant issued by American officials. The Obama administration made its request for Makled on Oct. 6, Mack said.

Laura Sweeney, a Justice Department spokeswoman, said she could not comment on a pending extradition. State Department spokesman Charles Luoma-Overstreet also said that he could not provide more details on the extradition request but that “we have made clear our law enforcement interest in prosecuting Makled.”

For years, U.S. and United Nations counter-drug officials have warned that Venezuela had become South America’s major transit point for Colombian cocaine bound for U.S. and European cities. In 2008, the Bush administration blacklisted three top aides to Chavez, accusing them of involvement in the drug trade and aiding Colombian guerrillas.

According to U.S. court documents, Makled offered payoffs to high-ranking Venezuelan military officers and other officials in return for being allowed to operate airstrips around the country.

Makled, who at one point owned an airline, has not been shy about elaborating for Colombian and Venezuelan reporters. He told the Caracas newspaper El Nacional and the Colombian television network RCN about his ties to key officers in Venezuela’s security services. Among the highest-ranking officials to benefit from payoffs, he told reporters, was Justice Minister Tareck El Aissami.

In his most recent interview, which was to be aired Sunday night on Miami-based Univision’s “Here and Now,” Makled talked about paying off 40 generals. “The government of Venezuela, the generals, are narco-traffickers,” he said. “They are the ones who control the laboratories in Venezuela.”

El Aissami has denied Makled’s allegations. Venezuelan officials did not respond to requests for interviews to discuss the case.

On Friday, Colombia’s justice minister, German Vargas Lleras, said a final decision on Makled’s extradition would be made this month and that it would be based on Colombian law. He did not eleborate, but the law’s tenets give more weight to the country where the most serious crimes occurred.

In New York, where an indictment against Makled was unsealed Nov. 4, Makled stands accused of flying cocaine to the United States. The Venezuelans, though, want him in connection with two killings, as well as trafficking large loads of cocaine.

Makled’s lawyer in Bogota, Miguel Angel Ramirez, said Makled is calling on Venezuela to respect his rights and that his trial should be public. “What he assures is that in Venezuela there is a powerful apparatus of corruption of which he has been a part,” Ramirez said. “He says that ‘if I’m a narco-trafficker, then all the government people are narco-traffickers.’  ’’

But Roger Noriega, a former U.S. assistant secretary of state critical of Chavez, said he does not expect Makled’s allegations to get a fair hearing in Venezuela, where the justice system is controlled by the presidency. Noriega said U.S. investigators have been carrying out extensive investigations to unravel the role of Venezuelan officials in drug trafficking. Makled, he said, would have helped advance those cases. “You can’t make the case with intelligence, you can’t make the case with documents,” he said. “You need witnesses. And Makled has been auditioning for the role for the last six months on Colombian television.”