Former Utah Gov. Jon Huntsman addresses the Faith and Freedom Coalition in Washington, D.C. In the upcoming Republican primaries, limits on carbon emissions — which Huntsman once supported — are not expected to be a pivotal issue. Win McNamee/Getty Images hide caption

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A laboratory technician counts isolated Escherichia coli bacteria. Oleg Popov/AP hide caption

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House Republicans leave the White House on June 1, after a meeting with President Obama about the debt ceiling. Charles Dharapak/AP hide caption

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President Obama and first lady Michelle Obama sample Guinness at a pub in the village of Moneygall, Ireland. Obama's great-great-great grandfather Falmouth Kearney was a shoemaker in the town until 1850, when he left for the United States. Jewel Samad/AFP/Getty Images hide caption

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A youngster runs past the soon-to-open Obama Cafe in Moneygall, Ireland, on Saturday. President Obama is due to visit the village, the ancestral homeland of his great-great-great grandfather, as part of his 24-hour visit to Ireland on Monday. Matt Dunham/AP hide caption

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Delaware County District Attorney Patrick Meehan (from left) and Gail Willard (mother of slain athlete Aimee Willard) accompany Sen. Rick Santorum as he introduces "Aimee's Law" along with Republican Arizona Rep. Matt Salmon at the county courthouse in Media, Pa., in 1999. The bill encourages states to keep murderers and sexual predators behind bars. William Thomas Cain/AP hide caption

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Demonstrators hold signs at a protest against the U.S.-Colombia Free Trade Agreement (FTA) near the White House in 2009 during a visit by then-Colombian President Alvaro Uribe. Nicholas Kamm/AFP/Getty Images hide caption

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President Barack Obama waves from Air Force One before taking off from Reno, Nev., Thursday. Pablo Martinez Monsivais/AP hide caption

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House Budget Committee Chairman Paul Ryan (R-WI) takes questions in reaction to President Obama's speech on a federal spending plan at the Capitol on Wednesday. J. Scott Applewhite/AP hide caption

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At a House Budget Committee hearing in February, Rep. Paul Ryan (R-WI) holds up a Congressional Budget Office report on the federal budget. Alex Wong/Getty Images hide caption

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President Obama displays his Nobel Peace Prize during a ceremony in Oslo in December 2009. During his acceptance speech, the president discussed the concept of a "just war," saying: "There will be times when nations — acting individually or in concert — will find the use of force not only necessary but morally justified." Susan Walsh/AP hide caption

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A $5 per gallon price is posted at a gas station in Belmont, Calif., on Wednesday. Paul Sakuma/AP hide caption

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