5 to 10 if the pass Health Care
15 to 30 if they don't
Unemployement stays above 10% through November 25- 40
There is a double dip recession/Depression 50-100
100 seats? Even in the horrible Democratic years between 1994 and 2006, Democrats never fell below 203 seats.
While obviously they don't have most of the blame now, the last time that the Democratic party was blamed for a depression during a midterm election was 1894. Democrats had a truly epic loss, going from 61% to 26% in that election.
http://en.wikipedia.org/wiki/United_States_House_of_Representatives_elections,_1894
That depression was far worse, and furthermore, the GOP was an acceptable alternative, even in parts of the South at that point(and it was this GOP resurgence among white voters in the south which led to Jim Crow). The GOP does not even exist in places like Massachusetts and Rhode Island, or in urban seats. The GOP frankly is unlikely to have anywhere near enough serious candidates to win 276 seats. Even if unemployment was at 15%.