Very believable, I have been calling this likely to lean R all along, and now we have two polls showing Heidi trail, TOO POLARIZED! We need to cut our losses here and in MO (not as much in MO but still) and fight like hell to defend the rest of the seats, and pickup AZ and NV.
I think ND would be one of the less costly states to compete in, so I'm not sure why Dems would need to cut their losses. Heitkamp raised and spent about 5.4 million in her whole 2012 campaign. Since then, she's raised 6 million and has 3.7 million on hand. I think her campaign should be able to get the resources it needs pretty easily without hurting Dem chances in other places.