I don't buy NC and maybe this democratic lean is because it's an RV poll.
Who knows who really will vote?
Just think about it: a 'likely voter' could be someone who hasn't missed a vote in seventy years -- not even for a local millage. That's as reliable a voter as there is, right?
That voter is at least 91 years old, and might not make it to the polls this year or any subsequent year.
Now what about the newly-registered voter this year? That could be a late registrant, but someone convinced that we have the most important Presidential election ever.
...Other 'likely voters' might be moving from one state to another. Someone once a likely voter in Wisconsin becomes a likely voter in Minnesota.