FILE - In this March 17, 2018, file photo, Sen. Heidi Heitkamp, D-N.D., arrives for the state Democratic party convention in Grand Forks, N.D. Heitkamp, in one of the most challenging Senate re-election races this yea... That's what the North Dakota Democrat in one of the most Donald Trump-friendly states says, though it would seem she also doesn't have that luxury of avoiding the resistance. The first-term U.S. senator, among the most vulnerable in her party seeking re-election this year, is maneuvering herself at once as an ally of the Republican president on policy, and a polite opponent at other times.