Senators approved the pact, the biggest free-trade deal in a decade, by a narrow 54-45 vote Thursday, with a tough battle seen in the House of Representatives, probably later this month.

The Dominican Republic-Central American Free Trade Agreement (Cafta) was approved by a 25-16 vote in the House Ways and Means Committee, although some analysts see a more difficult battle on the House floor.

Still, the Bush administration appears close to winning a victory after pressing for more than a year, portraying it as an economic gain for the United States and as a foothold for free-market capitalism in the pact countries -- the Dominican Republic, Nicaragua, El Salvador, Honduras, Costa Rica and Guatemala.

Backers also argue the trade measure is a way to fend off the threat of Chinese textile exports by spurring further integration of US yarn and textile producers with low-cost garment makers in the Central American and Caribbean nations.

Cafta is seen as a stepping stone for a wider Free Trade Area of the Americas and a test of US credibility in bringing about a freer global trading system under the Doha Round of talks under the World Trade Organization.

Additionally, some have been arguing the measure is needed for economic stability and security in the region.

"We're talking about stability, stability within these countries and our own national security," said Senator Pat Roberts, chairman of the Senate Intelligence Committee.