Students protest the rising costs of college loans in Los Angeles in 2012. Citing bank bailouts, the protesters called for student debt cancellations. David McNew/Getty Images hide caption

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Donald Trump wears what's become a campaign signature: his "Make America Great Again" hat. Part of making the country great again, Trump says, is implementing his hard-line immigration plan. Scott Heppell/AP hide caption

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Republican presidential candidate Rand Paul wants to run for both his Kentucky Senate seat and the White House, but a current state law prohibits him from doing so. Charles Krupa/AP hide caption

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Republican presidential candidate and Wisconsin Gov. Scott Walker speaks at the Iowa State Fair, where he encountered protesters over his record in Wisconsin. Charlie Neibergall/AP hide caption

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Donald Trump continues to lead in the polls and on Sunday released his first policy position — a conservative proposal on immigration. Seth Wenig/AP hide caption

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Sen. Bernie Sanders, I-Vt., has gotten some of the biggest and most devoted crowds of the 2016 presidential race, including in Portland, Ore., this month, where he drew more than 19,000. Troy Wayrynen/AP hide caption

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Former Florida Gov. Jeb Bush speaks during the first Republican presidential debate Thursday in Cleveland. Bush touted his jobs record in Florida. Andrew Harnik/AP hide caption

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A supporter waves a Cuban flag in front of the country's embassy after it reopened for the first time in 54 years on July 20 in Washington, D.C. The embassy was closed in 1961 when U.S. President Dwight Eisenhower severed diplomatic ties with the island nation after Fidel Castro took power in a communist revolution. Mark Wilson/Getty Images hide caption

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An honor guard from the South Carolina Highway Patrol lowers the Confederate battle flag, removing it from the Capitol grounds on July 10. John Bazemore/AP hide caption

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Ben Carson is the only African-American major candidate running for president in 2016. He grew up poor in Detroit in the 1960s and paved his own path. Jonathan Bachman/AP hide caption

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In a campaign video, Rand Paul uses a chainsaw to shred 1,700 pages of what he says represents the federal tax code. Paul is offering a flat-tax plan that fits on one page. Rand Paul campaign video hide caption

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Donald Trump has landed in controversy since getting into the Republican race for the presidential nomination, but he has only seen his standing increase. Frederic J. Brown/AFP/Getty Images hide caption

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"When Mexico sends its people, they're not sending their best. ... They're bringing drugs; they're bringing crime, [bringing] their rapists. And some, I assume, are good people," Donald Trump said while announcing his campaign last month. Paul J. Richards/AFP/Getty Images hide caption

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Republican presidential candidate and TV personality Donald Trump arrives by escalator to the tune of "Rockin' in the Free World." Musician Neil Young did not approve of his song choice. Brendan McDermid /Reuters/Landov hide caption

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