Power joined the Obama State Department transition team in late November 2008. She served as Special Assistant to the President and Senior Director for Multilateral Affairs and Human Rights on the National Security Council from January 2009 to February 2013. In April 2012, Obama chose her to chair a newly formed Atrocities Prevention Board. As U.N. ambassador, Power's office focused on such issues as United Nations reform, women's rights and LGBT rights, religious freedom and religious minorities, refugees, human trafficking, human rights, and democracy, including in the Middle East and North Africa, Sudan, and Myanmar. She is considered to have been a key figure in the Obama administration in persuading the president to intervene militarily in Libya. In 2016, she was listed as the 41st-most powerful woman in the world by "Forbes".