President Barack Obama and first lady Michelle Obama with Malia, right, and Sasha, left, greet children dressed like elves at the annual Christmas in Washington taping at the National Building Museum in Washington, Sunday, Dec. 11, 2011. Host Conan O'Brien, Justin Bieber, Cee Lo Green, Jennifer Hudson, Victoria Justice and The Band Perry were to perform. (AP Photo/Jacquelyn Martin)
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