President Barack Obama stands with first lady Michelle Obama, former first lady Barbara Bush, former President George W. Bush, and Laura Bush at the dedication of the George W. Bush presidential library on the campus of Southern Methodist University in Dallas, Thursday, April 25, 2013. (AP Photo/Charles Dharapak)

Photo by: Charles Dharapak

President Barack Obama stands with first lady Michelle Obama, former first lady Barbara Bush, former President George W. Bush, and Laura Bush at the dedication of the George W. Bush presidential library on the campus of Southern Methodist University in Dallas, Thursday, April 25, 2013. (AP Photo/Charles Dharapak)