Is that what it said? How can you trail a successor when that is the person who comes *after* you? Heh. Maybe there was a typo there. In any case apparently if the governor runs against Dorgan he can win, otherwise the incumbent is in good shape, sadly. At least as of now. Though even Sen Lincoln is considered vulnerable against weak, underfunded opponents so I say they should go after Dorgan too, even if they can’t get a top tier challenger.
It's like the pick up line "Hi, you look like my next ex-girlfriend".
If you are an incumbant and you are trailing your challenger by 19 points a year before the next election, you are indeed trailing your successor. That is an unbelievable gap, particularly for an incumbant. (The reason being is that an incumbant is a known quantity (i.e. name recognition is pretty maxed out) and an incumbant can not gain a lot of ground. 19 points is a ton of ground to make up, and I don't know that any incumbant could do so.)