The Vote Rick Santorum's endorsement regret: Why he backed Romney in '08

Rick Santorum is surging in Iowa just before the caucuses Tuesday, giving Mitt Romney a run for his money. Back in 2008, Santorum gave Romney something else: his support.

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Rick Santorum may be emerging as one of Mitt Romney's toughest rivals in Iowa, but back in 2008, he was something else: a supporter.