Changing electoral demographics:
The attacks on Sotomayor are not going to help this, especially in the face of the further radicalization of the Republican Party:
No matter what the specific amounts are (somewhere between a net of 6% and 8%), roughly half of the Democratic electoral improvement since the dark days of 1988 has come from demographic change, rather than from either infrastructure / strategy / activist improvements, or from poor Republican governing performance. Further, this demographic change is actually more problematic for Republicans than the other two areas, because it requires changing the coalitions rather then developing better infrastructure or simply hoping that Democrats can’t get the economy going again. It is an underlying problem Republicans face, and which requires them to break out of the ongoing Nixon-McGovern framework of American political coalitions. From now on, the McGoverns are just going to keep winning, even if they were to nominate another Michael Dukakis.