Charlie Cook's 2012 election predictions

Charlie Cook looks at the math and presents his case here:

In a bell curve of House probabilities, the best-case scenario for Republicans would be no net change. The best case for Democrats would be a gain of about 15 seats. Near the top of the bell curve, the most likely outcome today appears to be a Democratic gain of five to 10 seats. . . .

the best-case scenario for Democrats would seem to be a net loss of three seats. This would take the Senate makeup from 53 Democrats and 47 Republicans to a 50-50 tie. The best-case outlook for Republicans seems to be a net gain of six seats, which would give the GOP 53 seats in the next Senate. At this admittedly early stage, the most likely outcome is a net Republican gain of four or five Senate seats, yielding them a 51-49 or 52-48 majority. . . .