Last fall, Samantha Power, a professor of public policy at Harvard University, told The Chronicle that advising Sen. Barack Obama on foreign policy was one of the greatest experiences of her professional life. But she added that she was deeply anxious that her blunt style would someday get the campaign into trouble:

[N]ew technologies make the candidate-adviser relationship more perilous than it once was. In theory a student in one of Ms. Power’s Harvard courses might post one of her classroom comments (perhaps wildly out of context) on a blog and create a news-media storm within hours. “That’s the one thing that terrifies me,” Ms. Power says. “That I’ll say something that will somehow hurt the candidate.” She says that in public lectures and interviews, she sometimes fights the urge to make unkind statements about other candidates. “That’s just not Obama’s style,” she says. “Left to my own devices, I’d articulate my frustrations in a much harsher way.”

Today that fear came to pass. Ms. Power resigned from Mr. Obama’s campaign after The Scotsman, an Edinburgh newspaper, quoted her describing Sen. Hillary Clinton as “a monster.”

Her statement of resignation said in part, “Last Monday I made inexcusable remarks that are at marked variance from my oft-stated admiration for Senator Clinton and from the spirit, tenor, and purpose of the Obama campaign. And I extend my deepest apologies to Senator Clinton, Senator Obama, and the remarkable team I have worked with over these long 14 months.”

Ms. Power, who is affiliated with Harvard’s Carr Center for Human Rights Policy, won the Pulitzer Prize for her 2002 book, “A Problem From Hell”: America and the Age of Genocide. Last month, she published Chasing the Flame: Sergio Vieira de Mello and the Fight to Save the World. Just four days ago, a New York Times article casually predicted that she “could very well end up in [Mr. Obama’s] cabinet.”