The Gallup poll that Doug pointed to not only gives Republicans a 6-point advantage in the generic ballot (which is 13 points among independents), but it also finds that Republicans are more enthusiastic about voting by a 15 point margin. As Gallup points out in its analysis of the results, typically Republicans do better in turnout in midterm elections than polling models predict, so a even a tie in the generic ballot would normally suggest Republicans winning a higher percentage of the actual vote. So a six-point lead, if it holds up, could mean an overwhelming victory by the GOP in November. Yet Gallup notes that, “it is not clear whether the recent shift marks the beginning of a lasting change in the structure of the race or perhaps a short-term response to political events such as the Obama administration’s handling of the BP oil spill. The latter appeared to be the case earlier this year as Republicans built a small lead after the healthcare bill’s passage into law, but the slight bump for the GOP among registered voters did not last.”