Republican presidential candidates at the final GOP before the South Carolina primary on Saturday at the Peace Center in Greenville, South Carolina. Spencer Platt/Getty Images hide caption

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Then-presidential candidate Rick Santorum speaks to reporters in the spin room Jan. 14 after the "undercard" portion of the Fox Business Network Republican presidential debate in South Carolina. Scott Olson/Getty Images hide caption

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Donald Trump's paternal grandparents, Friedrich Trump and Elisabeth Christ, came from the southwest German village of Kallstadt. Thomas Lohnes/Getty Images hide caption

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Bernie Sanders and Donald Trump deliver victory speeches at their respective watch parties in New Hampshire. Jewel Samad/AFP; Joe Raedle/Getty Images hide caption

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Republican presidential candidates, from right, Ohio Gov. John Kasich, former Florida governor Jeb Bush and Sen. Marco Rubio, R-Fla., participate Jan. 28 in a GOP debate in Des Moines, Iowa. Rubio's strong third-place finish in Iowa has given him momentum and more backing from the same establishment Republicans that Bush and Kasich need for their campaigns to survive. Scott Olson/Getty Images hide caption

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Donald Trump and Russian President Vladimir Putin have exchanged compliments. In the words of one Putin adviser, "he more carefully listens to so-called 'silent majority' of the American nation, who don't want conflict with Russia." Robert F. Bukaty/AP hide caption

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Former first lady Barbara Bush, mother of Republican presidential candidate Jeb Bush, campaigns with her son at a town hall meeting at West Running Brook Middle School in Derry, N.H. Jacquelyn Martin/AP hide caption

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Jeb Bush holds a campaign town hall meeting at the Alpine Club on Monday in Manchester, N.H. Chip Somodevilla/Getty Images hide caption

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