the main cause of Democratic distress isn't promoting liberal legislation but simply being in charge when bad things are happening to the nation's economy.
So, we have high unemployment, and the party in power is being blamed. Nothing else to see here. Move along.
This is an off-topic blog post. That is, I have no valuable expertise on the topic of elections and public opinion, which is Sabato's profession. Yet, I worry that his interpretation misses something. It ignores the insurgency that is taking place within the Republican Party, which is described by Mark Ambinder and by Angelo Codevilla. At one point in the podcast, Codevilla says something to the effect that 3/4 of Republican voters are against what Republicans have done in recent years.
I suspect, also, that when the dust settles, the Democrats will turn out to have done relatively better among the unemployed than among other voters in the November election. My guess is that the electoral damage of high unemployment will come not from economic pain per se as from the loss of credibility for those who claimed that stimulus was the answer. In the 1930's, there was plenty of high unemployment to frustrate voters, but Roosevelt had not lost credibility. Same with Reagan in 1982.
An interesting question is why Roosevelt remained popular. I would like to think that the atmosphere he created was "Give me the benefit of the doubt," as opposed to "I know best." Note how quickly he lost his grip on popular support when he over-reached with the "court-packing plan."
Also, I have been saying for a long time that the 2010 election will be the first opportunity for voters to express antagonism toward the Wall Street bailouts. In 2008, your choice was either: John McCain, who supported the bailouts; or Barack Obama, who supported the bailouts, retained Ben Bernanke, and gave Timothy Geithner a promotion.
For a politician, it may help to think in terms of a bank account. When you do something popular, you make a deposit. When you do something unpopular, your make a withdrawal.
You can claim that without the bailouts, the situation would be much worse economically. But politically, the bailouts were a big withdrawal, and they never got paid back. Neither Roosevelt nor Reagan inherited this sort of deficit of political legitimacy. President Obama and the Democrats did. They rushed to do the stimulus, cap-and-trade, and health care reform without having any political legitimacy in the bank.
To me, that is what is creating the political dynamic this fall.