American University’s Brian Schaffner has a nice graph illustrating the implications of the GOP’s defeat in the special election in Mississippi’s first district. He plots the vote for GOP House candidates in open seat elections in 2006 against President Bush’s vote total in the district in the 2004 election and then superimposes the MS-1 result in red:

Candidates who performed as well as Bush would appear on the diagonal line from the bottom left to the upper right. Deviations below that line indicate underperformance; those above that line represent overperformance. As Schaffner notes, only three open seat candidates in 2006 performed as poorly as Greg Davis did last week (and that doesn’t take into account the fact that the special election was in Mississippi). Given the way the fundamentals are looking, we may be looking at a historic pro-Democratic swing in November.