1. The House seems to be holding fine for GOPers. There are a ton of Dem incumbents at or below 45 percent. In a wave election, nearly all of those folks lose. In 2006, there were a ton of GOP incumbents polling between 46 and 48 percent -- many of them lost. Note: if the Republicans only were to win the 48 seats that voted for a Democrat for Congress and McCain for President, they'd pick up 48. Even if Democratic enthusiasm matches Republican enthusiasm, the game board is tilted toward Republicans.
On the flip side, there is evidence that African Americans are becoming more engaged and more interested in voting. Given that they vote 90 percent or so for Democrats, having their base get more motivated -- even late -- means something.
Of course, most of the House battleground districts have low African American percentages, so it is less of a boon than in other situations.
2. The Senate landscape still tilts toward Republicans -- the polls look particularly strong in Arkansas, North Dakota, Indiana, and Wisconsin. Republicans are also positioned to win four of the five open seats they're defending -- FL, NH, OH, and MO. That leaves eight races -- Republicans needs six of these -- KY, PA, IL, CA, WA, CO (where polls show a Bennet surge of late), WV, and NV. Republicans have an edge in WV and NV among these seats.