A new News Watch and the Chiesman Center for Democracy at the University of South Dakota/Mason-Dixon Polling and Strategy poll in South Dakota finds Mike Rounds (R) leading Brian Bengs (I) in the U.S. Senate race, 56% to 37%.South Dakota Senate RaceMike Rounds (R) 56% Brian Bengs (I) 37% News Watch and the Chiesman Center for Democracy at the University of South Dakota/Mason-Dixon Polling and Strategy poll · likely voters · ±4.5%