By NEDRA PICKLER
The Associated Press
Friday, March 7, 2008 11:49 AM

A Barack Obama adviser has resigned after calling rival Hillary Rodham Clinton "a monster."

A campaign official told The Associated Press Friday that Samantha Power's resignation is effective immediately.

Power told The Scotsman that Clinton is a "monster" who will stoop to anything to win. She tried to make the remark off the record, but the Scottish newspaper printed it anyway. She apologized in a statement and the campaign decried the remark.

Power is a foreign policy adviser to Obama and a Pulitzer Prize winner.