Former House speaker Newt Gingrich (right) and Herman Cain during a Republican presidential debate Nov. 22, 2011, in Washington, D.C. Mandel Ngan/AFP/Getty Images hide caption

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Republican presidential candidate, Herman Cain campaigned Wednesday in Dayton, Ohio. He told a Fox News interviewer he would decide in the next week whether to stay in the GOP race. Al Behrman/AP hide caption

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Hillary Clinton's "inevitability" became less certain after a debate in Philadelphia at Drexel University in October 2007. William Thomas Cain/Getty Images hide caption

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Republican Presidential candidate Herman Cain greets supporters at a campaign rally outside of Wings Plus on Wednesday in Coral Springs, Fla. Joe Raedle/Getty Images hide caption

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