WASHINGTON (AP) — A White House official says President Barack Obama will name former aide Samantha Power as the U.S. ambassador to the United Nations.

Power will replace Susan Rice, who will take over as Obama's national security adviser. The official says Obama will announce both appointments from the White House Wednesday afternoon.

Power is a longtime Obama adviser who worked on his 2008 presidential campaign and ran the human rights office in the White House. She left the administration in February but was considered the favorite to replace Rice at the U.N.

The official insisted on anonymity in order to confirm the appointment before it was publicly announced.