WASHINGTON, DC - JANUARY 20:  Former U.S. President Barack Obama (R) congratulates U.S. President Donald Trump after he took the oath of office on the West Front of the U.S. Capitol on January 20, 2017 in Washington, DC. In today's inauguration ceremony Donald J. Trump becomes the 45th president of the United States.  (Photo by Chip Somodevilla/Getty Images)