At this stage in the election cycle, just like in baseball's spring training, fans love to see a new phenom catch fire. Wisconsin Gov. Scott Walker, sporting a Milwaukee Brewers jersey in 2013, seems to be the rookie to watch in the 2016 presidential race so far. Manuel Balce Ceneta/AP hide caption

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Barack Obama as a presidential candidate in Selma, Ala., in 2007 re-creating a voting rights march that was violently repressed by state troopers in 1965. Roberto Schmidt/AFP/Getty Images hide caption

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Britain's Finance Minister George Osborne greets New Jersey Gov. Chris Christie outside 11 Downing Street in London. Christie had a bumpy trip after he said parents should "have some measure of choice" when it comes to vaccinating their children. Adrian Dennis/AFP/Getty Images hide caption

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Wisconsin Gov. Scott Walker spoke about taking on public employee unions, and the protests that followed, at a recent candidates forum in Iowa. He said what people may not know is that protesters — as many as 1,000 of them — showed up outside his home while his family was there. He says he also received death threats. Scott Olson/Getty Images hide caption

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