Costa Ricans vote Sunday on whether to ratify a free-trade trade deal with the United States that has sharply divided the nation between those who say it would generate prosperity and critics who fear it would hurt farmers and local businesses. Costa Rica is the only one of the six signatories to the U.S.-Central American Free Trade Agreement, known as CAFTA, that has yet to ratify it. The deal is in effect in the Dominican Republic, Guatemala, Honduras, Nicaragua and El Salvador.

With polls showing that Costa Ricans are poised to reject the pact, Costa Rica's president and U.S. officials have appealed for voters to back the deal.

On Saturday, the White House said if Costa Ricans vote against joining the agreement, the Bush administration will not renegotiate it.

The pact would "expand Costa Rica's access to the U.S. market, safeguard that access under international law, attract U.S. and other investment and link Costa Rica to some of the most dynamic economies of our hemisphere," White House press secretary Dana Perino said in a statement.

U.S. officials also suggested they may not extend trade preferences now afforded to Costa Rican products and set to expire next September.

Despite its conflicts over trade, Costa Rica fares better than other Central American countries: It has a thriving eco-tourism industry, maintains relatively high-paying jobs and is a magnet for Salvadoran and Nicaraguan migrants.