Jeb Bush Jeb Bush

Jeb Bush speaks to an audience of voters on Feb. 18 in Columbia, S.C. Bush dropped out of the GOP presidential race two days later, after finishing a distant fourth in the state's primary. Spencer Platt/Getty Images hide caption

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Spencer Platt/Getty Images

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

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Spencer Platt/Getty Images

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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Jewel Samad/AFP; Joe Raedle/Getty Images

Republican Chris Christie of New Jersey has invested nearly his entire campaign on New Hampshire. A poor result will almost certainly effectively end his candidacy. Robert F. Bukaty/AP hide caption

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Robert F. Bukaty/AP