BISMARCK, N.D. - The first of what is expected to be many polls looking at the U.S. Senate candidates for North Dakota was released Tuesday, showing incumbent Sen. Heidi Heitkamp, D-N.D., with a narrow lead over Rep. Kevin Cramer, R, N.D. Heitkamp leads Cramer 43 to 40 with 17 percent of voters still undecided, which is unsurprising as the election is still months away. The poll was conducted online by Gravis Marketing with 385 respondents and a margin of error of 5 percentage points. Heitkamp trails among Trump supporters by a wide margin but has a lead among white voters....