The latest from Public Policy Polling has the GOP enjoying a 47-42 lead over Democrats on a generic congressional ballot, on the strength of a more unified base and a 37-31 advantage among independents.

Meanwhile, Charlie Cook writes that he expects Republicans to pick up between 30 and 40 seats in the House based on a consideration of all 435 individual races, but adds that a national climate in which Republicans are more unified and likelier to turn out than Democrats could push those gains higher.

And Rothenberg Political Report agrees:

Substantial Republican gains are inevitable, with net Democratic losses now looking to be at least two dozen. At this point, GOP gains of 25-30 seats seem likely, though considerably larger gains in excess of 40 seats certainly seem possible.
We’ve moved 44 seats toward the Republicans and only 4 toward the Democrats.

Oh, and the positive developments don’t stop at the midterms. Another PPP survey shows four top GOP presidential contenders with leads (Mitt Romney, Mike Huckabee) or dead-heats (Sarah Palin, Newt Gingrich) against Obama.