First lady Michelle Obama hugs an unidentified student after she took part with 6th and 7th grade District of Columbia school children in a performance in the East Room at the White House, in Washington, Wednesday, Feb. 18, 2009, by Sweet Honey in the Rock, an African American female a cappella ensemble. (AP Photo/Ron Edmonds)

U.S. President Barack Obama, first lady Michelle Obama and daughters Malia (L) and Sasha arrive on Air Force One at O'Hare International Airport on February 13, 2009 in Chicago, Illinois. The Obama family is visiting Chicago for the first time since the Inauguration last month. (Photo by Pool/Getty Images North America)

U.S. President Barack Obama, first lady Michelle Obama and daughters Malia (R) and Sasha (L) arrive at O'Hare International Airport on February 13, 2009 in Chicago, Illinois. The Obama family is visiting Chicago for the first time since the Inauguration last month. (Photo by Brian Kersey-Pool/Getty Images) *** Local Caption *** Sasha Obama;Malia Obama;Michelle Obama;Barack Obama (Photo by Pool/Getty Images North America)

(L to R) U.S. President Barack Obama while walking to Marine One with his daughter Malia, first lady Michelle Obama and daughter Sasha on the South Lawn of the White House February 13, 2009 in Washington, DC. Obama is traveling with his family to Chicago for Presidents' Day Weekend. (Photo by Brendan Smialowski/Getty Images) *** Local Caption *** Sasha Obama;Malia Obama;Michelle Obama;Barack Obama (Photo by Brendan Smialowski/Getty Images North America)

U.S. President-elect Barack Obama kisses his daughter Sasha, 7, (L) at a gathering of supporters before the Obamas embark on a whistle-stop train trip to Washington beginning at the 30th Street Station on January 17, 2009 in Philadelphia, Pennsylvania. The Obamas will travel by train from Philadelphia to Washington with a stop in Wilmington, Delaware, to pick up Vice President-elect Joe Biden, going forward to Baltimore, Maryland before ending the trip in the nation's capitol. (Photo by William Thomas Cain/Getty Images) *** Local Caption *** Sasha Obama;Barack Obama (Photo by William Thomas Cain/Getty Images North America)

First Lady Michelle Obama (L) and her daughter Sasha Obama (R) attend an event in the East Room of the White House on February 18, 2009 in Washington, DC. Mrs. Obama hosted an event honoring African American History Month by welcoming 6th and 7th grade DC school children to a performance at the White House. (Photo by Mark Wilson/Getty Images) *** Local Caption *** Sasha Obama;Michelle Obama (Photo by Mark Wilson/Getty Images North America)

First Lady Michelle Obama (L), with daughters Malia Obama (C) and Sasha Obama (R) attend an event in the East Room of the White House on February 18, 2009 in Washington, DC. Mrs. Obama hosted an event honoring African American History Month by welcoming 6th and 7th grade DC school children to a performance at the White House. (Photo by Mark Wilson/Getty Images) *** Local Caption *** Sasha Obama;Malia Obama;Michelle Obama (Photo by Mark Wilson/Getty Images North America)