Since April, I’ve been predicting a House GOP pick-up in the low 50s. Subsequent months of data seemed to strengthen the likelihood of a 52-seat-or-so outcome without greatly expanding the field of Democratic representatives at genuine risk, but only recently has the direness of the party’s electoral predicament really crystallized. In all, a remarkably high number of Democratic seats — 118 to be exact — are now, in one way or another, in play. Forty-four seats are now pure toss-ups or worse.The last month has been particularly bad for Democrats. From April to August, the average rating (solid/likely/lean/tossup) of Democratic...