As the United States and other member countries of the World Trade Organization continue negotiations on a new global-trade agreement in Geneva, about two dozen groups representing American colleges are beseeching U.S. officials to avoid making concessions that would threaten the autonomy of higher-education institutions. During the latest round of talks on the General Agreement on Trade in Services, or GATS, U.S. officials have cited higher education as one of many services the United States is willing to make more accessible to other countries. The offer could make it easier for foreign students and instructors to enter the United States, or for foreign-based distance-learning institutions to offer courses to American students. The proposal is backed by for-profit higher-education institutions and testing companies in the United States that seek to grow internationally. They hope that in return for U.S. concessions, other member countries of the trade group will be more open to U.S.-based institutions' operating in their countries. But the American Council on Education and the Council for Higher Education Accreditation have written to Susan C. Schwab, the U.S. trade representative, saying that the offer could drive a wedge between private and public colleges, as well as undermine state regulations governing higher-education institutions. Twenty-one other college groups also signed the letter, including the Association of American Universities and the American Association of State Colleges and Universities. The groups are particularly assertive because they say the Bush administration is trying to use fast-track negotiating authority to push a trade deal through Congress.