Four advocacy organizations representing thousands of colleges and universities sent a letter to U.S. Secretary of State Colin L. Powell in June asking that he postpone the State Department's requirement that nearly all international visitors to the United States undergo an in-person interview before they get their travel visas.

College officials are afraid that the new mandate will lead to increased delays that will keep students and scholars from arriving on campuses in time for the fall term. They fear that that, in turn, will discourage foreign students and scholars from coming to American institutions to study, teach, and do research.

"If the system is backed up interminably, we're not aware of what we can do to compensate," said Martin C. Jischke, president of Purdue University.

The presidents of the Association of American Universities, the American Council on Education, the National Association of State Universities and Land-Grant Colleges, and the Council of Graduate Schools signed the letter. The presidents suggested in the letter that the State Department delay the interview requirement until sufficient resources could be devoted to the task. They also suggested that the department phase in the requirement, based on the students' country and their potential security risk.

There is already some evidence that the policy is starting to hinder foreign students' ability to arrive for the fall term. The letter mentions a student from India admitted to Purdue University who was informed by a State Department consular office in India that the earliest he could schedule his interview would be August 21. Purdue's fall term starts on August 25.

Given the interview backlog that already exists, it is not certain whether the student will be seen on that earliest-possible date, said Mr. Jischke, the university's president. Even if he is, he said, he would have only a few days to make his arrangements to travel.

Foreigners who do not make it to campuses on time face certain risks, said Michael A. Brzezinski, director of the office of international students and scholars at Purdue. Depending on the institution and the academic department that accepts them, he said, graduate students must arrive before classes start to secure their teaching and research assistantships. Undergraduate students who miss more than one week of class, he said, have a difficult time catching up.