Wisconsin Gov. Scott Walker speaks at the 40th annual Conservative Political Action Conference in National Harbor, Md., on Saturday, March 16, 2013. (AP Photo/Carolyn Kaster)

Photo by: Carolyn Kaster

Wisconsin Gov. Scott Walker speaks at the 40th annual Conservative Political Action Conference in National Harbor, Md., on Saturday, March 16, 2013. (AP Photo/Carolyn Kaster)