A power struggle over the future of Dartmouth College’s board of trustees could end up in court. Leaders of the Dartmouth College Alumni Association are threatening to bring a lawsuit against their alma mater for changing the structure of the board of trustees, a move they say would dilute alumni power in determining college policies.

A lawsuit would escalate a debate over who controls the future of the fabled Ivy League college: the administration or its alumni, a reputably loyal and active group. In a letter sent via e-mail to the Dartmouth community last weekend, the chairman of the board, Charles Haldeman, announced the college is increasing the number of board-appointed trustees to 16 from eight, essentially stacking the board in a way that diminishes the power of trustees chosen by the alumni.

Mr. Haldeman said the decision was made to control the “destructive politicization of trustee campaigns that have hurt Dartmouth.” The Dartmouth College Alumni Association fired back earlier this week, announcing that it was considering filing a lawsuit against the college.

The restructuring of the board comes in response to the alumni’s selection of four candidates who in recent years have petitioned to be included on the ballot alongside candidates nominated by the alumni association.

“The actions of Dartmouth’s trustees are more in keeping with the conduct of a totalitarian state than with a college dedicated to educating leaders of the world’s greatest democracy,” an alumni association officer, Frank Gado, said. “Dartmouth doesn’t trust its graduates with a meaningful vote.”

A number of active alumni, who last year helped raise a school record of $159 million in charitable gifts, say they now are considering withdrawing their financial support for the school.

“I will not contribute to the school until the alumni’s voice is restored,” a businessman, Joseph Asch, said. Mr. Asch said he has contributed more than $500,000 to the college over the past 10 years.

“A lot of alumni said that they are taking Dartmouth out of their wills,” an alumni-elected board member who petitioned to be included on the ballot, Stephen Smith, said. Mr. Smith, a professor at the University of Virginia School of Law, is the most recently elected Dartmouth trustee that petitioned to be included on the ballot. The college has recently reached a 50% mark of alumni giving, Mr. Smith said, and now risks falling below that mark.

In recent years, the four trustees elected by the alumni, who together represent libertarian voice on the board, have split with the other trustees on their vision for Dartmouth’s future.

The college’s administration has emphasized turning the college into a small research university that could attract federal grant money and boost its ranking. Many alumni have been fighting to preserve the undergraduate liberal arts tradition. The petition trustees have also voiced concerns over what they consider to be objectionable limits on free speech on campus.

“As goes New Hampshire, so goes the nation,” a Dartmouth alumus who is the managing editor of the New Criterion, James Panero, said. Mr. Haldeman, he said, “has rolled the tanks of Tiananmen onto Dartmouth Green.”

“It’s like abolishing the House of Commons and making it all the

House of Lords,” a journalist who graduated from Dartmouth in 2002, Michael Weiss, said. “There’s a great academic tradition, and I wouldn’t want to see that legacy diminished, but this raises all kinds of questions about giving money — where’s the money going to go? Who’s making the decisions about the future of the school?”

A Dartmouth alumnus who graduated in 1997, David Bruder, said he has given several hundred dollars a year to the college for 10 years. “It’s very hard to stop giving money and hurt the college that I care about, but since the college has affectively taken away my vote, this might be the only language they’ll listen to,” Mr. Bruder said.

Dartmouth officials said that it was too early to tell how the decision would affect future fund raising. “Some people will be offended by it and reduce or eliminate their giving,” the co-chairman of the Dartmouth College Fund, Michael Biondi, said. “I think a large number believe it’s the right thing to do and will increase their support for the college.”

Giving alumni a large say in the governance of the college has been an important part of the Dartmouth tradition, and one of the aspects that distinguishes the college from other Ivy League schools. Since 1891, Dartmouth alumni have elected half of the board’s members. The New Hampshire governor also sits on the board, as does the college president, and eight trustees appointed by the board.

The policy was unchallenged until 2004, when a libertarian businessman, T.J. Rodgers, mounted a successful election for the office, challenging the candidates nominated by the alumni association. In 2005, a former speechwriter for Ronald Reagan, Peter Robinson, and a law professor, Todd Zywicki, successfully ran for board posts on petition ballots. Mr. Smith is the most recently elected candidate that petitioned to be included on the ballot.