But Hollander said that to his knowledge, Rudenstine has never before had to leave work because of severe exhaustion.

Much of Rudenstine's time in the last several months has been spent fundraising for the University's $2.1 billion capital campaign.

"The effect on campaign depends on how long he's out," Daniel said. "If it's a short time period, I don't think it will be [affected], at least we certainly hope not."

Carnesale will take Rudenstine's place at a meeting of Ivy League presidents today. He will also attend this weekend's Board of Overseers meeting in place of Rudenstine.

"I will perform the responsibilities of the office of the president," Carnesale said. "This is not a waiting period. We will continue on course."

"We'll miss his leadership for this period," Carnesale added. "I expect to be talking with him, though the frequency of the conversations will be determined more by his physicians than by me."

Rudenstine is scheduled to make a decision concerning the future of Harvard's relationship with ROTC. He was to make a recommendation to the Faculty Council in December.

Carnesale said that Rudenstine's report is "just finished" and will be distributed to the Faculty Council before their next meeting.

"His recommendation will be contained in a document... to be distributed," Carnesale said in an interview after the press conference. "We don't have to do artificial things about presenting it."

The president was also planning a fundraising trip to Latin America in January.

"I don't think any actions like [canceling the trip] have been taken," Carnesale said.

The only light moment of the press conference was when a reporter asked about the line of succession for the president's job.

"I can't tell you about the line of succession," Carnesale joked, "but the Speaker of the House is in there somewhere."

A cursory search of presidential files in the Harvard University archives today found no examples of presidents taking leaves because of illness.

Carnesale said at the press conference that President Derek C. Bok took a sabbatical in 1987, during which former-Dean of the Faculty Henry Rosovsky assumed the role of acting president.