Bush said he personally delivered this message to Uribe during a phone call earlier Tuesday. Colombia has received some $5 billion in U.S. aid to counter the drug trade and battle leftist guerrillas since 2000, and Uribe is considered a right-leaning ally of Bush's in a region dominated by leftist politics.
Relations have hit a new low between Uribe on one side and Chavez and Ecuador's President Rafael Correa on the other. Bush, making a rare and hastily scheduled personal appearance to describe a private conversation with a foreign leader, added himself to Uribe's side.
The raised tensions were triggered by a weekend raid by Colombian troops into Ecuador that killed a top commander of the FARC, Colombia's main rebel group, which had set up a camp there.
Since then, Colombia and Ecuador have traded accusations and Chavez, sympathizing with the leftist rebels, ordered thousands of troops to move toward Venezuela's border with Colombia.
"America will continue to stand with Colombia as it confronts violence and terror and fights drug traffickers," Bush said.
Colombian military officials have said that U.S. satellite intelligence and communications intercepts have been key to putting the FARC on the defensive.
Bush said one of the chief ways that Washington can help Uribe is for Congress to approve a free-trade deal with Colombia. Though signed by the two countries in 2006, Capitol Hill's Democratic leaders have refused to pass the agreement, citing human rights violations in Colombia and its standing as the deadliest country in the world for organized labor.
Supporters have argued that the pact would level the playing field for U.S. products by requiring Colombia to lower or eliminate tariffs on them when many Colombian products already get such preferences in the American market.
Bush has sought to add new urgency to the debate by proclaiming the issue also a matter of national security - and he used the crisis in South America as an opportunity to do so again.
"If we fail to approve this agreement, we will let down our close ally, we will damage our credibility in the region, and we will embolden the demagogues in our hemisphere," he said.
"(Uribe) told me that the people across the region are watching to see what the United States will do. So Republicans and Democrats in Congress need to come together and approve this agreement."
