President Obama answers questions during his news conference at the White House on Tuesday. Pablo Martinez Monsivais/AP hide caption

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President Obama during his news conference Tuesday at the White House. Larry Downing /Reuters /Landov hide caption

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President Obama joked at the White House Correspondents' Dinner that he had experimented with bangs to liven up his second term, stealing a fashion tip from the first lady, Michelle Obama. CSPAN hide caption

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President Obama and former President George W. Bush at the dedication of the George W. Bush library in Dallas. Alex Wong/Getty Images hide caption

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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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President Obama speaks Thursday during an interfaith service at Cathedral of the Holy Cross in Boston. C.J. Gunther /EPA /LANDOV hide caption

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President Obama leaves the White House briefing room Tuesday after making a statement about the bombings at the Boston Marathon. Mark Wilson/Getty Images hide caption

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Health and Human Services Secretary Kathleen Sebelius (center), flanked by Centers for Medicare and Medicaid Services Acting Administrator Marilyn Tavenner (left) and Food and Drug Administration Commissioner Margaret Hamburg, speaks during a budget briefing in Washington on Wednesday. Manuel Balce Ceneta/AP hide caption

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President Obama prepares to depart San Francisco on Thursday. Jewel Samad/AFP/Getty Images hide caption

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President Obama in Denver on Wednesday. Jewel Samad /AFP/Getty Images hide caption

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