Biden says Rice has, in his words, "the absolute, total, complete confidence of the president." He says that when Rice speaks about foreign policy, nobody doubts that she's speaking for President Barack Obama.
Biden spoke Tuesday night at a gala for the Joint Center for Political and Economic Studies. The think tank focuses on African-American issues and is honoring Rice with an award.
Biden's comments come a day before a House hearing on the deadly assault on a U.S. mission in Benghazi, Libya.
Rice was vilified for making widely debunked claims after the attack that protests, not terrorism, precipitated the raid. The incident cost Rice an opportunity to become secretary of state.