A new analysis by Gallup, compiled from their national polling done all this year, shows just how extensive the Republican Party's drop in voter self-identification has been, with decreases in nearly every demographic.
Compared to 2001, when George W. Bush first took office as president, GOP self-identification has fallen by ten points among college graduates, nine points among those 18-29 years of age, nine points in the Midwest, six in the East, five in the West, and even four points in the South. Married people identifying as Republicans have decreased by five points, and the difference is eight points among the unmarried. The list goes on and on.
In 2001, voters were 33% Democratic, 32% Republican, and 34% independent, with a Democratic edge of 45%-44% after leaners were pushed. But now, it's 36% Democrats, 27% Republicans and 37% independents, with a huge Democratic advantage of 53%-39% with leaners.
The only bright spots for the GOP are three base groups: Frequent churchgoers, with no decrease at all; conservatives, with only a one-point decrease; and voters 65 years of age or older, with a one-point decrease. It should also be noted that they've only gone down one point among non-whites -- but this is because they didn't have much party identification there to begin with.
Late Update: This post originally referenced the party-leaner numbers for college graduates, rather than for all Americans. The error has been corrected.