Every time a special congressional election is held, political journalists and pundits instinctively, almost compulsively, feel an urge to apply its results to a larger, national narrative. They/we can't help it! It's a tricky business, though. A single, local race held months or years away from the next regularly scheduled national election doesn't necessarily mean anything. Its outcome could depend on local issues and/or unique demographics and/or particularly weak/strong candidates, none of which would really portend much outside the district.
What's more useful for predictive purposes is looking at special elections as a group. There have been four of them so far this year. In May, Democrat Kathy Hochul exceeded expectations and won in a normally Republican upstate New York district. In July, Democrat Janice Han won in a Democratic district, but not by as much as she should have. And last night, the GOP scored two victories: A Republican won in Nevada's second district, and Republican Bob Turner defeated Democrat David Weprin in Anthony Weiner's former ninth district seat. Numbers wizard Nate Silver looked at how all these races would have been expected to go down in a vacuum. And it's not good for the Democrats.
One crude way to forecast the results you might expect to see out of a House race is through its Partisan Voting Index, or P.V.I., a measure of how the district voted relative to others in the past two presidential elections ....
Republicans have overperformed the P.V.I. baseline by an average of 7 percentage points across the four races. That squares with what we saw in 2010, when Republicans won the popular vote for the House by an aggregate of 7 percentage points.
If you don't count Hochul's victory in May a very different political environment then Republicans have outperformed expectations by an average of 14.6 points in special elections over the past two months.
As to why Democrats are underperforming recently, it's no mystery to most people: President Obama. As Politico reports:
Even before the polls closed, the recriminations — something short of panic, and considerably more than mere grumbling — had begun. On a high-level campaign conference call Tuesday afternoon, Democratic donors and strategists commiserated over their disappointment in Obama. A source on the call described the mood as “awful.”
“People feel betrayed, disappointed, furious, disgusted, hopeless,” said the source ...
“I think every election reflects on the person in charge, but do I think it is an overall statement on the president alone? No,” said [House Democratic Whip Steny] Hoyer. “Do I think it will be interpreted as being a statement on Obama? That’s probably correct.”
A senior Hill Democratic aide was more direct in attempting to explain the New York loss: “The approval ratings for the guy at the other end of Pennsylvania Avenue cratered.”
A Turner consultant, Steve Goldberg, validated that assessment: “It was all Obama — not even a thought of anything else.”
The silver lining for Obama is that the presidential election isn't today. It's a year from now. He doesn't have any more Bin Ladens to kill — hell, that only impressed people for a few days anyway — but nobody can predict what the next year has in store for him. Which doesn't mean he shouldn't start worrying.