FARGO – A new independent poll released today indicates North Dakota’s U.S. Senate race is a dead heat between Republican Rep. Rick Berg and Democrat Heidi Heitkamp. Fargo-based Valley News Live and Bismarck-based KFYR-TV commissioned a poll of 625 likely North Dakota voters this week, just days before the statewide primary election. The poll found Heitkamp with 47 percent of the support from likely general election voters, while Berg had 46 percent. Seven percent remain undecided in the race, with about five months left until November. Mason-Dixon Polling & Research, of Washington, D.C., conducted the telephone survey June 4-6. The...