All this Monday Morning Quarterbacking is making me sick! It was a horrible night for the GOP and for conservatives. However, it fits perfectly within the historical context of how elections go for a president six years out, especially a president conducting a war.
Just remember the same thing happened to Reagan in 1986. The American electorate is a fickle lot, and the pendulum will again swing in our direction. Few of the losses were severe, percentage-wise, we still have two out that are 'too close to call' but which we will probably lose, seating Leahy as Chair of Judiciary.
No single person or candidate is to blame in this... tho I do wish Tony Snow had gotten to the White House a year earlier (I know he couldn't have, with his surgery) but the WH lost a lot of ground not properly expressing its positions, its successes, and in dealing with the WH press corps.
It's been pointed out that Congress has never changed hands during war (until now).