Student protesters and trustees of the University of the District of Columbia yesterday began negotiations that could end the four-day-old student occupation of a campus building, with the students apparently easing away from their demand that the appointed trustees resign.

The two sides began discussions about 2 p.m. yesterday on 37 demands that ranged from adding employees in the admissions office and student involvement in the evaluation of faculty to expanded library hours and the creation of an African-American studies program. The list of demands grew to 39 by 4 p.m.

It was the first bargaining between the two sides since the student occupation began on Wednesday.

Students and staff appeared optimistic yesterday that the talks would head off a possible confrontation between students and police that the trustees have indicated might occur if the protesters have not left the building by tomorrow morning.

"While these negotiations are still continuing, all of the students are in imminent danger," said Mark Thompson, who has emerged as the leader of the protesters. "We have been threatened by the board of trustees and the mayor that the police could move in at any given moment."

But trustee A. Knighton Stanley said the board's statement that the university would reopen tomorrow was not a threat. "What we have done is exercise our responsibility as trustees of the university," Stanley said.

The alleged threat of force and a claim by students that the university was manipulating the climate control system in the occupied student-affairs building to make it uncomfortable have raised anxieties, Thompson said.

"They are putting the heat on when it is hot and putting the air on when it is cold," Thompson said. "This is very much like a situation in South Africa."

UDC spokesman John Britton denied the allegation.

Some students who have been inside the building since shortly before noon on Wednesday said that Friday night was particularly trying for the protesters.

Friday night "was really tough," said one student, who asked that her name not be used because protest leaders have asked students not to talk to the media. "It was getting factionalized, tempers were flaring."

Food and supplies have not been a problem for the protesters, who have received donations from businesses, individuals and groups, including the Nation of Islam. But the simple matter of being holed up in a building for four days with no end in sight appeared to be wearing on some.

Foreign students in particular were worried about the possibility of arrest and how that would affect the status of their visas, some said.

But one student said the protesters' spirits were boosted yesterday morning when they learned that two Barry appointees to the board, Arthur M. Reynolds and Lourdes Miranda, had resigned.

Publicly, the students are not backing off their demand for more resignations. But sources said it appeared the students may be willing to accept a proposal to enlarge the board to about 21 members, including more students.

Through it all, some students said, the 25-year-old Thompson has helped pull the group together.

Thompson is no stranger to organizing. In late August, when a group announced the formation of a coalition to urge a boycott of the annual Labor Day celebration in Virginia Beach by black students, Thompson was a key participant.

Thompson also was at the center of the action in May, when a national group of college students planned a protest march on Washington.

"He's got the look, he's got the sound, he's got the popular ideas," one of the UDC protesters said yesterday.