Research 2000 for Daily Kos. 10/12-14. Likely voters. MoE 4% (no trend lines)
Beau Biden (D) 45
Mike Castle (R) 46
Well, it couldn't be any tighter than that in this marquee matchup. Castle easily leads other potential match ups (Castle 51 Kaufman 37, Castle 49, Carney 41, Castle 51 Coons 39), but the Biden-Castle one is most likely because the political establishment loves its monarchies, and so do the voters. Interestingly, while Castle has solid Republican support (82-9), Biden gets less than three-quarters of Democrats (72-21). Independents lean toward Castle (48-40). If Biden brings Democrats home, it gets much harder for Castle to win.
Both Castle and Biden have nearly identical approval ratings as well, providing perhaps the most even matchup of the cycle. While some prognosticators are already slotting this race as a "lean Republican", the data suggests this is about as pure a "toss-up" as you can have in politics.
We also polled Democrat John Carney in two potential House matchups, and the Democrat has a huge early lead. That race isn't expected to be competitive giving Democrats an easy pickup of Castle's vacated seat.