"Wisconsin Gov. Scott Walker is reflected by glass before speaking at a leadership summit in Nashua, New Hampshire, on April 18, 2015. Walker, who rose to national fame by taking on unions in one of the most blue-collar states, <a href=""http://www.cnn.com/2015/07/13/politics/scott-walker-2016-presidential-announcement/"" target=""_blank"">officially became a presidential candidate three months later.</a>"