WASHINGTON, DC - JUNE 15: U.S. President Barack Obama, first lady Michelle Obama, their daughters Malia Obama and Sasha Obama and Michelle's mother Marian Robinson walk across the South Lawn before boarding Marine One and departing the White House June 15, 2012 in Washington, DC. The first family will travel to Chicago for the weekend before Obama travels to Mexico Sunday. (Photo by Chip Somodevilla/Getty Images)