Around the country, there have been 8 legislative special elections since March 1, 2011 in districts that voted in November of 2010 and had a traditional two-party race. (Meaning a Republican and a Democrat rather than only one candidate from a major party, or a third party candidate grabbing a significant number of votes.) Those races make for an interesting comparison between now and November, and may well foreshadow what happens here in six months.
The 8 races all came from the West, the Midwest, and the Northeast. Some Southern races would have been interesting and instructive, but none have happened. What those races show is a substantial swing in favor of Democrats. Here are the districts, and their respective Democratic percentages:
District: 2010 Dem % 2011 Dem% Change
California AD-4 36.65 44.62 D+7.97
Maine HD-11 26.08 40.75 D+14.67
Maine SD-7 48.37 67.87 D+19.50
Mass. HD-10 68.86 67.64 R+1.22
Minnesota SD-66 76.15 80.25 D+4.10
NH HD-4 42.69 58.18 D+15.49
Wisconsin AD-83 21.28 25.83 D+4.55
Wisconsin AD-94 41.12 53.69 D+12.57
Average 45.15 54.85 D+9.70
Interesting numbers, but again, none of them are from the South, so it may not mean much. We'll see when November rolls around.