The president of Colombia will try to convince doubtful U.S. legislators to give him more money in his drug war by telling them the billion they've already contributed is helping in the crackdown.

The U.S. invested $1.3 billion in President Andres Pastrana's anti-drug initiative last year, but confidence in the plan has faltered in recent months both because of the current war in Afghanistan and because of shaky evidence that drug trafficking in Colombia is decreasing.

In meetings with congressional leaders and administration officials, Pastrana also plans to push for lower trade barriers for the Andean region and discuss Colombia's problems with terrorism, according to Colombian ambassador Luis Moreno.

In a whirlwind trip to the United States, Pastrana has meetings scheduled in Washington Thursday and Friday, then heads to New York for the U.N. General Assembly meeting Saturday and a meeting with President Bush on Sunday.

His visit follows a vote by the Senate last month to cut $164 million of the Bush administration's $731 million request to fight drugs and boost the economy in the Andean region. About half that money was destined for Colombia. The House has called for smaller cuts and conferees will try to work out the differences.

Moreno said Pastrana will talk to lawmakers about the country's progress in fighting drugs, but won't get into the specifics of how much more money should be spent.

"We don't want to get into the middle of the discussions of the Senate and the House," he said. "I think the administration has made a point as to its desires. Let the Congress decide what they think is best."

Lawmakers from both parties were strongly behind the $1.3 billion Colombian anti-drug package, approved last year. Most of the money was for helicopters and training for Colombian counternarcotics troops. The soldiers fight guerrillas who partly finance their 37-year-old insurgency by protecting drug fields and traffickers.

But congressional interest in the South American country has waned. Senators say there is no sign the aid has reduced the flow of drugs. Concerns remain about Colombia's human rights record and about the United States getting drawn deeper into Colombia's civil war. And the U.S. government still hasn't spent much of the money in the original package, making it difficult to justify additional spending, lawmakers say.

In addition, the focus on terrorism and the fighting in Afghanistan have reduced interest in spending more money on the drug fight.

When Sen. Bob Graham, D-Fla., tried to restore the administration's full $731 million, his proposal was rejected in a 72-27 vote.

"(Colombia) has a lesser priority," Graham said Tuesday. "I have a hard time understanding what is behind this retreat from our commitment to fighting drugs, guerrillas and terrorists in the Andean region."

Supporters of Colombian aid say it has already shown some successes in boosting coca eradication. They note the $1.3 billion aid package was considered the start of a five- or six-year project aimed at cutting Colombia's coca production in half. Cutting funding now would undermine chances of meeting that goal, they say.

"Without maintenance and spare parts for the 50 helicopters soon to be delivered, Colombia's difficult struggle against spreading narcoterrorism will grind to a halt," said Sam Stratman, spokesman for the Republican-led House International Relations Committee.

The debate over the anti-drug aid comes as the Bush administration considers providing additional funds to help Colombia fight terrorism. The two main guerrilla groups and the paramilitary umbrella organization there are on the State Department's list of terrorist groups.

Moreno said Colombia could use training and equipment to help its police investigate kidnappings and to protect oil pipelines, power lines and railroad tracks. Kidnappings and extortion are important sources of revenue for Colombian combatants, along with drug trafficking.

But Moreno said it was unlikely Pastrana, in his U.S. visit, would discuss specific proposals for fighting terrorism. "That is something that is very preliminary right now," he said.

The Associated Press contributed to this report.