President Alvaro Uribe has been trying to calm fears in South America
Colombia says it has completed talks with Washington on allowing US troops to use seven of its military bases.
Under the deal, the US military will be able to operate on Colombian soil to tackle drug-trafficking and terrorism.
A number of South American countries have condemned the plan and Argentina has said the bases are "not helpful".
Venezuelan President Hugo Chavez has expressed fears the move would amount to preparation for an invasion of his country by US forces.
Colombia's foreign ministry said that Bogota had agreed the text of the deal with the US.
"This agreement reaffirms the commitment of both parties in the fight against drug-trafficking and terrorism," the ministry said in a statement.
The deal will now be reviewed in both countries before being signed.
'Climate of unease'
Last week, Colombian President Alvaro Uribe visited several of his South American neighbours to try to calm fears over the proposed deal with Washington.
On Monday, South American leaders at a regional summit had reiterated concerns over the deal.
Mr Chavez warned that "the winds of war were beginning to blow" across the region.
The Brazilian president, Luiz Inacio Lula da Silva, called for a meeting between US President Barack Obama and the region's leaders, saying the "climate of unease disturbs me".
Washington wants to use Colombia as a regional hub for operations to counter drug-trafficking and terrorism.
The US has been forced to look for a new base for such operations after Ecuador refused to renew the lease on its Manta base, which the US military was using.