Democrat Roy Cooper is leading Republican Michael Whatley in the race for North Carolina's open U.S. Senate seat, according to a head-to-head poll by Opinion Diagnostics, a Boston-based polling company run by political advisors to Republican politicians in Massachusetts and North Carolina. The poll surveyed about 830 North Carolina voters and found Cooper leading Whatley 50% to 42%, with 8.2% undecided. The race to replace outgoing Republican Sen. Thom Tillis will also feature Libertarian Shannon Bray. The Senate Leadership Fund plans to spend $71 million to help Whatley's campaign, while Democrats see North Carolina as a key opportunity to flip from red to blue this November.