DES MOINES, IA - AUGUST 16:  Republican presidential hopeful Ben Carson signs a poster with a picture of him and the other Republican candidates at the Republican Party of Iowa booth while touring the Iowa State Fair on August 16, 2015 in Des Moines, Iowa.  Presidential candidates are addressing attendees at the Iowa State Fair on the Des Moines Register Presidential Soapbox stage and touring the fairgrounds. The State Fair runs through August 23.  (Photo by Justin Sullivan/Getty Images)