According to the latest Gallup survey, affiliation with the Democratic Party has dropped from a high of 50 percent in 2008 to 43 percent in 2011. This is lower than it was in June, but well within the average for the last two years:
The details are straightforward: Democrats remain "less white, more female, more liberal, less religious, and less likely to be married than the general population." Further, the Democratic Party remains disproportionately liberal and nonwhite. What's significant is that the proportion of liberals and nonwhites has grown since 2008, from 33 percent to 36 percent. In addition, the Democratic Party has seen a corresponding decrease in the number of whites who identify with the party – from 66 percent to 63 percent. The proportion of liberals has also grown since 2008, from 35 percent to 37 percent.
By and large, this is just a long way of saying that the Democratic Party has lost significant support from white, conservative, and moderate Democrats. These voters have either become independents or have moved their support to the Republican Party. In all likelihood, these are people who have left the Democratic Party out of frustration with the slow pace of economic growth. The good news for Democrats, as you can see in the graph above, is that they maintain an affiliation advantage over Republicans -– the bad news is that Democrats have less space to manuever in states like Pennsylvania and Ohio, where the median voter is more conservative than the Democratic Party as a whole. With lower support among those voters, the path to 270 electoral votes becomes much more difficult.