HOUSE DEMOCRATS....Did congressional Dems underperform this election compared to Barack Obama? Should they have won even more than 20 additional seats? Andrew Gelman cries foul:
The only trouble with this theory is that it's not supported by the data. Obama won 53% of the two-party vote, congressional Democrats averaged 56%. The average swing of 5.7% from Democratic congressional candidates in 2004 to Dems in 2008 was actually greater than the popular vote swing of 4.5% from Kerry to Obama.
I think this is basically right, but I want to add something. Andrew compares the average district vote in each state, and for technical reasons he thinks this is the right measure. I, however, prefer something cruder: total congressional vote, which turns out to be a pretty good predictor of total House seats won by each party.
So how did Dems do? In 2004 they lost to Republicans by 2.2 percentage points. In 2006 they won by about 7.4 points, an astonishing swing of 9.6 points. This year they won by about 8.2 percentage points, an even more astonishing swing of 10.4 points since 2004 and, as Andrew points out, bigger than the 8.7 point swing from Kerry to Obama.
So I guess my question to the skeptics is: Just how much do you think the Dems should have won by? Ten points is an enormous margin, far bigger than any party has enjoyed for the past two decades. If that's underperforming, I'll take it.