Samantha Power, President Obama's nominee to replace outgoing United Nations Ambassador Susan Rice, has focused her career on the study of genocide and humanitarian intervention, As an academic, a journalist and an activist, Power holds strong beliefs about human rights and the interventionist influence of the United States. Indeed, it was Power, along with then-Secretary of State Hillary Clinton and Susan Rice, that pressured President Obama to use NATO forces against Muammar Gadhafi in Libya.   If Power is confirmed, she faces a number of challenges to her humanitarian, interventionist vision. She may find herself debating policy with some of the dictators she has sought to bring down: until Libya's civil war and Gadhafi's death, the dictator's apologists represented Libya at the United Nations.    Kurt Volker  understands the challenges Samantha Power might face. Volker served as the U.S. ambassador to NATO from 2008 to 2009. He's currently the executive director of the McCain Institute.