August 31, 2015
The Monmouth University Poll of likely Iowa Republican caucus goers finds Ben Carson and Donald Trump tied for the top spot. This marks the first time since July 26 that a poll in any of the first four nominating states has not shown Trump with a nominal lead. Not surprisingly, given the top two contenders in the poll, most Iowa Republicans prefer someone without a traditional political pedigree.
(Monmouth University Poll)
Ben Carson, Carson Campaign Press Release - Poll: Carson Tied for Lead in Iowa Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/312687