President Obama stands with former presidents George W. Bush, Bill Clinton, George H.W. Bush, and Jimmy Carter 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)
President Obama stands with former presidents George W. Bush, Bill Clinton, George H.W. Bush, and Jimmy Carter 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)
President Barack Obama and first lady Michelle Obama stand with former Presidents George W. Bush, George H.W. Bush, and their wives, former first ladies Barbara Bush, and Laura Bush amd bow their heads in prayer 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)
Former Vice President Dick Cheney, center, shakes hands with former British Prime Minister Tony Blair during the dedication of the George W. Bush presidential library on the campus of Southern Methodist University in Dallas, Thursday, April 25, 2013. Former President George W. Bush's daughter Jenna Bush Hager is at right. (AP Photo/Charles Dharapak)
Former Secretary of State Colin Powell, center, flanked by former Attorney General John Ashcroft, right, and former Secretary of State James A. Baker III, listen during 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)
House Speaker John Boehner of Ohio, left, and Texas Gov. Rick Perry stand at the end of 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)
New Jersey Gov. Chris Christie and wife Mary Pat arrive 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)
Republican strategist and former White House senior adviser Karl Rove arrives 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)
Former Ghana President John Kufuor, left, speaks with former Labor Secretary Elaine Chao 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)
