The Bush administration has reached a free-trade agreement with four Central American countries, setting up a tough trade fight in Congress in an election year. The trade accord -- reached just weeks before the 10th anniversary of the North American Free Trade Agreement -- would allow more than 80 percent of U.S. consumer and industrial products into Guatemala, Nicaragua, El Salvador and Honduras duty-free as soon as it went into force. That figure would rise to 85 percent within five years and 100 percent in a decade. U.S. agricultural products would take considerably longer to reach duty-free status, as long as 18 years, in large part because U.S. trade negotiators insisted on protecting the American sugar market from Central American exports.