Ms. Hagan’s gains among this group are particularly important in an off-year election, since in 2008, Ms. Hagan did not fare well among voters over age 30. Her entire margin came from 18- to 29-year-olds who supported her by an astounding — and not replicable — 47-point margin, according to the exit polls.

The idea that Ms. Hagan might be doing well among older people isn’t completely inexplicable. Although North Carolina seniors reliably vote Republican in federal elections, Democrats still have a voter registration advantage, as they do across much of the South. It’s not a small edge, either, with 51 percent of the older voters registered as Democrats compared with just 33 percent as Republicans. And so far this year, Democrats have generally been faring a little better among seniors than they have been over the last few cycles.

But Ms. Hagan’s success among this demographic is still a little hard to explain. She has not had a Senate career aimed at winning over conservative white Democrats, either. She’s not Senator Mark Pryor of Arkansas, for example. She’s a fairly mainstream Democrat running a fairly mainstream campaign.

If Ms. Hagan were an especially popular figure, who had capitalized on the typical advantages of incumbency by improving her image and appeal over the past six years, then perhaps one could imagine how she was doing better than she was six years ago. But almost all of the available evidence suggests that Ms. Hagan’s ratings are just as mediocre as they were this spring.