Polls show changing American opinion on marijuana, and it's having an effect on politics. Leon Neal/AFP/Getty Images hide caption

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Sen. Rand Paul, R-Ky., center, meets with members of the Londonderry Fish and Game Club in Litchfield, N.H., on Jan. 14. Paul was one of three GOP presidential hopefuls who attended Sunday's semiannual gathering of David and Charles Koch's donor network in California. Jim Cole/AP hide caption

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Sen. Rand Paul takes the stage at the Conservative Political Action Conference in National Harbor, Md., Friday. For the second consecutive year, Paul won the event's straw poll. Chip Somodevilla/Getty Images hide caption

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Sen. Rand Paul (R-Ky.) greets supporters during a tea party rally in front of the U.S. Capitol in June. Paul was a rising star in the tea party movement this year, filibustering a CIA nomination in March. Mark Wilson/Getty Images hide caption

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Sen. Strom Thurmond of South Carolina after his 24+ hour filibuster in 1957. He was a Democrat then. Later, Thurmond would switch to the Republican Party. AP hide caption

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An unmanned drone patrols the U.S.-Canadian border. Attorney General Eric Holder, in a letter to Sen. Rand Paul, R-Ky., said the president could in an "extraordinary circumstance" order a drone strike inside the country. U.S. Customs and Border Protection /AP hide caption

itoggle caption U.S. Customs and Border Protection /AP