With a sparkling intellect, a mane of auburn hair and a Pulitzer Prize-winning book to her credit, Samantha Power cut a disarming path just about anywhere she went.




Power's style won over many journalists, diplomats and one presidential contender. But outspokenness became her undoing, forcing Power on Friday to quit Barack Obama's presidential campaign after publication of an interview in which she called his Democratic rival, Hillary Rodham Clinton, "a monster."




The 37-year-old Harvard professor and Time magazine columnist gave up her position as a foreign policy adviser to Obama and apologized for describing Clinton in "such negative and personal terms."




But the trouble for Obama did not end there. In an overseas book tour earlier, Power also raised doubts about the candidate's position on Iraq, forcing Obama on Friday to assure the public that he had not weakened his resolve to withdraw troops from Iraq and "bring this war to an end in 2009."




At the end of another day of distraction for his campaign, Obama had lost one of his earliest, and certainly most charismatic, advisers. And Powers &

who two experts said might have lost her way at the fuzzy intersection of her multiple roles as author, journalist and campaign operative &

saw her comments open a new line of attack for Sen. Clinton of New York.




"If you are book writer promoting yourself and your work, you are supposed to be provocative and interesting and tell the truth," said Tom Rosenstiel, director of the Project for Excellence in Journalism. "Candidates are not there to speak the truth in all of its glory. They are there to win an election."




The contretemps over Power's words came just a week after another controversy erupted over whether Obama's top economic adviser had told Canadian officials that Obama did not fully embrace his own attacks on the North American Free Trade Agreement.




The missteps distracted from the candidate's push to regain momentum after losing primaries Tuesday in Ohio, Texas and Rhode Island.




"The problem for them is having a couple of these missteps at exactly the wrong time," said Joe Trippi, a top strategist for former Sen. John Edwards during his presidential run. Although he called attacks by Clinton on Obama's foreign policy experience "unfair," Trippi added: "It's not a good thing to have one of your leading foreign policy proponents saying things that you have to back away from or explain."




Obama and his erstwhile adviser met in 2005, after the senator became intrigued by her prize-winning "A Problem from Hell: America and the Age of Genocide." The two talked late into the night at a steakhouse, much of the conversation centering on her belief that the United States should have done more to stop the devastating killing in Darfur and other places.




If Obama has been dubbed the "rock star" candidate, Power might have been his rock star adviser. Born in Ireland and schooled at Yale and Harvard Law School, she founded the Carr Center for Human Rights Policy at Harvard. The Times of London said she would have fit right in to the Kennedy clan. She once played basketball with actor George Clooney, a fellow Darfur activist.




Although a member of Obama's inner circle, Power served as an unpaid adviser. She previously had confided to friends that she had ambitions to be secretary of State.




Her troubles began when she traveled to Britain to promote her latest book, "Chasing the Flame: Sergio Vieira de Mello and the Fight to Save the World," a biography of the dashing U.N. envoy killed at U.N. headquarters in Baghdad in 2003.




In a free-wheeling interview conducted Monday by The Scotsman newspaper, Power used an expletive to say the Obama campaign had blown the recent primary in Ohio. She implied voters there had become "obsessed" with the economy and that Clinton had played on those concerns.




"She is a monster, too &

that is off the record &

she is stooping to anything," Power told political correspondent Gerry Peev. She added of Clinton: "The amount of deceit she has put forward is really unattractive."




Peev followed a standard journalistic practice in requiring interview subjects &

particularly political operatives &

to reach agreement in advance if they want to keep matters out of the public domain.




Writer Peev said in an interview Friday that she found Power "intelligent and likable," but that "it would be a disservice and dereliction of duty if I didn't run the quotes I have on my tape recorder."




Power said in a statement: "I made inexcusable remarks that are at marked variance from my oft-stated admiration for Sen. Clinton and from the spirit, tenor, and purpose of the Obama campaign. And I extend my deepest apologies to Sen. Clinton, Sen. Obama, and the remarkable team I have worked with over these long 14 months."




In a subsequent interview with the Boston Globe, Power said she had been tired from an overnight flight and also disturbed by news she received by phone during the interview about unspecified Clinton campaign tactics.




"I care passionately &

obviously, too passionately &

about the Obama campaign," Power told the Globe, adding that she had resigned to remove "all the distractions that I had brought."




(optional add end)




The distractions did not end immediately, however.




The Clinton campaign Friday helped publicize that Power also appeared to back away from Obama's previously stated plan to bring all troops home from Iraq within 16 months.




Pressed by an interviewer on the BBC's "Hard Talk" program, Power said: "You can't make a commitment in March 2008 about what circumstances will be like in January of 2009," adding that the Obama plan was a "best-case scenario" that he "will revisit when he becomes president."




That led to a tit-for-tat on the campaign trail Friday, with Clinton saying in Hattiesburg, Miss., that the episode "raises disturbing questions about what the real planning and policy positions inside the Obama campaign happen to be," and Obama responding from Casper, Wyo., that he would withdraw from Iraq by next year.




Power was so busy making headlines with those comments that yet another zinger, delivered in an interview with an English magazine, did not get much notice Friday.




The New Statesman reported that Power was already talking about how staffers from a defeated Clinton camp might be integrated into the Obama campaign. While some would be welcome for their "technical expertise," the magazine reported Power as saying, others Clintonites would not fit in.




"We don't want to end up in a lowest-common-denominator operation," Power reportedly told the magazine, "which is what, I think, actually, really hurt her."