The democratic majority in congress is not just losing the support of moderates and independents anymore. Per gallup:
"Congress' job approval rating from Americans fell six points in the past month, from 24% to 18% -- the lowest reading in more than a year. Nearly 8 in 10 (78%) now disapprove. This decline in congressional approval is largely explained by a sharp drop in approval among rank-and-file Democrats, from 45% in January to 30% today."
In the 2006 elections republicans fared so poorly both because the democrats had a surge in voter turnout and because disaffected conservatives stayed home. We already knew the tea party turnout in 2010 is going to be huge. If the democratic base stays home because they're upset with congress too, 2010 will go from projecting republican gains to projecting a complete landslide. That doesn't bode well for central Texas democrats like Chet Edwards, who has already had retirement suggested to him by some traditional friends.
So what would a 2006-in-reverse election night look like? In 2006 the democrats picked up 31 seats in the house and 5 in the senate. A similar gain by the republicans this fall would leave them with 46 senate seats and 209 house seats. Both numbers would be slightly short of regaining a majority - and that's probably a good thing. Continued democratic dominance for another two years will allow them to continue getting the blame for the public's anger at the government. After the 1994 elections Newt Gingrich started getting blamed for the country's problems as much as Clinton did. That played a role in an unpopular at the time Clinton winning a second term two years later.
Besides, the current republican leadership still inspires little support from base conservatives even with big gains projected in November. Another two years in the political wilderness to do some soul searching might do them some good - or give the good conservatives in congress another two years to push them out.