President Obama, former presidents George W. Bush, Bill Clinton, George H.W. Bush and Jimmy Carter attend the opening ceremony of the George W. Bush Presidential Center on Thursday in Dallas, Texas. The Bush library, which is located on the campus of Southern Methodist University, with more than 70 million pages of paper records, 43,000 artifacts, 200 million emails and four million photographs. Alex Wong/Getty Images hide caption

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Former President George H.W. Bush in June. Michael Loccisano/Getty Images for HBO hide caption

itoggle caption Michael Loccisano/Getty Images for HBO

Who will be Romney's VP? The naming of his running mate is likely going to come in mid-August, after his foreign trip and the conclusion of the Olympics. Ken Rudin collection hide caption

itoggle caption Ken Rudin collection