CAMBRIDGE, Mass. – The resignation under pressure of the president of Harvard, Lawrence Summers, yesterday touched off widespread speculation about who might succeed him and whether the episode may have diminished the attraction of what has until now been one of the most coveted jobs in academia.

Among the names that quickly emerged as leading contenders to replace Mr. Summers were Nannerl Keohane, a member of the board that presided over his hiring and his departure, Lee Bollinger, president of Columbia University, and Drew Faust, dean of the Radcliffe Institute.

Asked how the storm surrounding Mr. Summers would affect the future governance of the Harvard, the chairwoman of the government department, Nancy Rosenblum, said, “That’s the $64,000 question, isn’t it?”

“One view is the faculty now feels itself empowered and really will now present a challenge to a new president. The other is this was a very particular set of circumstances and lack of fit,” she said. “I’m hopeful it will be the latter.”

Some at other universities said the scenario that led to Mr. Summers’s resignation will make it difficult for Harvard to find an assertive replacement. “There are two classes of university presidents: managers who may be good keep things going and keeping the budget in check, and visionaries,” a professor of economics and sociology at the University of Chicago, Gary Becker, said.

“In my judgment, too few visionaries are presidents of universities. This will give a signal that if you try to shake things up you’re going to face losing support,” Mr. Becker said.

An official with the American Council on Education, Sheldon Steinbach, said the development could cause some possible candidates for president to Harvard to shy away. “I think a lot of them will look at the experience Larry Summers had over the course of the last four years and will gauge whether they desire to have that job.”

Still, Mr. Steinbach said, Harvard has drawing power. “At the end of the day, Harvard is still Harvard. There will be probably many qualified individuals who will be happy to undertake what is the leadership of the world’s greatest university.”

Mr. Summers resigned after a renewed barrage of criticism from faculty members undermined confidence in his ability to govern America’s oldest and most highly esteemed university.

“I have reluctantly concluded that the rifts between me and segments of the Arts and Sciences faculty make it infeasible for me to advance the agenda of renewal that I see as crucial to Harvard’s future,” Mr. Summers said in an open letter. “I believe, therefore, that it is best for the university to have new leadership.”

The decision by Mr. Summers to leave his post after just five years came as professors at Harvard’s flagship school were preparing to vote next week on a motion of no-confidence in his leadership. Last March, a similar motion passed by a 218-to-185 vote after the university president drew fire for suggesting that innate differences between the sexes might explain part of the under-representation of women in fields such as math and science.

The five-member board that oversees Harvard said yesterday Mr. Summers’s resignation was accepted “with regret.” A letter released by the secretive panel, often referred to as “the corporation,” offered effusive praise for Mr. Summers, but referred only briefly and obliquely to the highly-public infighting that marked his tenure.

“While this past year has been a difficult and sometimes wrenching one in the life of the university, we look back on the past five years with appreciation for all that has been accomplished and for the charting of a sound and ambitious forward course,” the corporation members wrote. They said a former Harvard president, Derek Bok, had agreed to serve as an interim leader for the institution while a formal search is undertaken to replace Mr. Summers.

In a conference call with reporters, Mr. Summers suggested that his downfall was due to his aggressiveness in pressing for broad changes at the elite university. “I recognize that when you try to do a lot of things quickly, the virtue can be that a lot is able to happen quickly, but the consequences can be that various kinds of resistance can build up more quickly,” he said.

Mr. Summers’s initiatives included a sweeping review of the undergraduate curriculum and an aggressive expansion of Harvard’s presence in Boston’s Allston neighborhood, across the Charles River from the university’s main campus in Cambridge.

The real estate project is moving forward, despite regular complaints from some professors that they were left out of the process. Mr. Summers eventually retreated from the curriculum review, which has fizzled.

Another flash point has been Mr. Summers’s handling of personnel matters. A series of veteran administrators have stepped down after clashing with the university president. The latest such conflict, which resulted last month in the resignation of the dean of the faculty, William Kirby, is widely seen as triggering the series of events that culminated yesterday in Mr. Summers’s announcement.

The second no-confidence motion against Mr. Summers was filed after reports spread that Mr. Kirby was forced out. He declined to confirm the reports, but has acknowledged differences with his boss.

One of Mr. Summers’s supporters said yesterday that the president’s relationship with many faculty members became so frayed that it was difficult for him to carry out his duties.

“I think it’s a sad development for President Summers and for Harvard, but probably a necessary one,” Ms. Rosenblum, the government professor, told The New York Sun. “What keeps coming into my mind is that John Dunne poem, ‘Death Be Not Proud.’ Nobody can be proud of this outcome.”

While many attributed the Harvard leader’s demise to his management technique, some professors said yesterday that the anger towards Mr. Summers was driven by his refusal to adhere to doctrinaire left-wing political views common in academia.

“This was all about Larry Summers’s political incorrectness,” a renowned law professor, Alan Dershowitz, said. He pointed to the Harvard president’s comments on gender differences, his support for military training on campus, and his public suggestion that proponents of divestment in Israel were promoting anti-Semitism.

Mr. Dershowitz said corporation members would come to regret their actions. “They will pay a heavy price for this. It puts the political correctness police in charge of the campus,” he said.

Many of Mr. Summers’s backers said yesterday that it was a mistake for him to apologize last year when his statements on gender resulted in the first faculty vote. Others said Mr. Summers, who served as treasury secretary under President Clinton, was uncomfortable being defended by a small band of faculty conservatives. His alienation from those on both ends of the spectrum left him with a tenuous power base.

In recent days, members of Harvard’s law, design, medical, and dental faculties praised Mr. Summers and complained that they were being ignored while those at the faculty of arts and sciences, which oversees the undergraduate college, took center stage. “This is the first instance of an academic coup d’etat at Harvard,” Mr. Dershowitz said yesterday.

However, Ms. Rosenblum faulted faculty at the professional schools for remaining all but silent as the controversy simmered. “They been slumbering and feeling it wasn’t their fight,” she said. “They’ve been on notice for a year, so I have no sympathy for that.”

Mr. Summers said yesterday that he will leave his post in June and take a year’s sabbatical. He said he will accept Harvard’s offer that he return in 2007 with the title “university professor.”

Ms. Keohane, a leading contender to replace Mr. Summers, is a scholar of political philosophy and feminist theory who has served as president of Duke University and Wellesley College.

Mr. Bollinger, the president of Columbia, is another possibility, though his selection seems less likely since he was passed over during the search that selected Mr. Summers.

Even allies of Mr. Summers acknowledged yesterday that one factor that contributed to his early exit was his unusual ability to give offense over issues peripheral to his agenda. In a recent interview, an anthropology professor who clashed with Mr. Summers and subsequently quit as dean of Harvard’s graduate school of arts and sciences, Peter Ellison, recounted an early conversation in which Mr. Summers said professors in the social sciences could usually be ranked in terms of intellect.

“President Summers asked me, didn’t I agree that, in general, economists are smarter than political scientists, and political scientists are smarter than sociologists?” Mr. Ellison told the Boston Globe. “I laughed nervously and didn’t reply.” The former dean also accused Mr. Summers of governing in an autocratic style better suited to government than academia.

Mr. Summers was generally well liked by undergraduates, some of whom rallied to his defense last year. The student newspaper, the Harvard Crimson, reported that after yesterday’s announcement about 150 people gathered outside his office, including some who chanted, “Stay, Larry, Stay.”

In recent days, the criticism of Mr. Summers went beyond his management style and policies, taking aim at his basic capacity to lead the university. Last week, the professor who filed the most recent no-confidence motion, Judith Ryan, said Mr. Summers lacked the intellectual breadth necessary to be president of Harvard.

“At the heart of the matter right now is his relatively narrow education which makes it hard for him to relate equally well to all the disciplines in the college and in the faculty,” Ms. Ryan told the Crimson.

“He’s a brilliant man. I’m not saying I’m the ideal person, either. I’m saying that we have at Harvard College an ideal of a broad education that encompasses many different areas, and I think if one speaks to President Summers at length about some areas he’s not familiar with, he shows that he hasn’t really had the same kind of liberal arts education as we are trying to provide you people.”

Ms. Ryan, a professor of German and comparative literature, did not respond to a call seeking comment for this story, but other professors said they believed she was referring to the fact that Mr. Summers did his undergraduate studies at the Massachusetts Institute of Technology.

Mr. Steinbach rejected the suggestion that Mr. Summers, who was 28 when he won tenure from Harvard in economics, lacked the qualifications to lead the elite school. “This is a disparaging, despicable comment,” Mr. Steinbach said. “It’s absurd.”