Former President George H.W. Bush, wears pink socks as he is seated in a wheelchair with, from left, first lady Michelle Obama, President Barack Obama, former first lady Barbara Bush, and former President George W. 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)
President Barack Obama shares a laugh with former first lady Barbara 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)
From left, President Barack Obama, former president George W. Bush, former president William J. Clinton former President George H.W. Bush and former president Jimmy Carter arrive for the dedication of the George W. Bush Presidential Center Thursday, April 25, 2013, in Dallas. (AP Photo/David J. Phillip)
President Barack 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 listens as former President George W. Bush speaks during the dedication of the George W. Bush Presidential Center, Thursday, April 25, 2013, in Dallas. (AP Photo/Tony Gutierrez, Pool)
President Barack Obama speaks 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 embraces former President George W. Bush after he spoke 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, first lady Michelle Obama, former presidents George W. Bush, George H.W. Bush, former first ladies Barbara 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)
**FILE** Health and Human Services Secretary Kathleen Sebelius testifies on Capitol Hill in Washington on April 17, 2013, before the Senate Finance Committee hearing on President Barack Obama's budget proposal for fiscal year 2014. (Associated Press)
