Proud of it or not, gerrymandering works to the GOP's benefit. There are more utterly lopsided districts for the Dems than for the Republicanns, which means an enormous number of Dems votes are "wasted" on candidates that are sure to get 80%+ from their districts, giving the GOP an edge in the remaining, more contestable districts.
Between this "gerrymander effect" and the "registerd/likely voter effect," a 47-45% split in Gallup is, in fact, extremely good news for the GOP. ........and should be causing deep consternation among the Dems (who hopefully will continue to be focused on ever more creative ways to hate George Bush).