I was talking to a smart Democratic pollster the other day and asked him about whether polls are oversampling Democrats. His view is that they’re not. People who are telling pollsters that they’re Democrats right now are thinking about the question, he thinks, in light of their voting intentions. He thinks that the party i.d. number will go back to indicating long-term trends a while after the election.
Said pollster is a moderate, by the way, and worries that the Democratic House–he thinks they’ll have a solid majority–will not be a good face for his party.