Robert Novak's predition today is that Dems will win 20 seats in the House, and four in the Senate:

With hopes of the late comeback faded, the Republican strategy has changed from that of a quarterback on a fourth-quarter come-from-behind mission to that of an overwhelmed emergency medical technician performing triage on several dying patients. The only thought now is to minimize losses by plugging whatever holes can be plugged. Late decisions have to be made about who lives and who dies. The GOP has to decide where it can win, and it cannot afford to waste time or resources on those who cannot be saved. At this point, the best indication of how races are going is where the money is being spent.

If the election were held today, Democrats would gain control of the House of Representatives. Republicans -20, Democrats +20.

As for the Senate, Novak predicts four Dem pickups: The seats held by GOP incumbents Mike DeWine, Rick Santorum, Conrad Burns and Lincoln Chafee. Novak's full analysis here.