At Open Left, Chris Bowers makes a small but important point about the stability of public opinion polling, and the continuing narrow Democratic advantage in the generic congressional ballot, that we’ve recently seen despite the turbulence of events in Washington:
The continuing Democratic advantage is significant since polls of “all adults” have almost entirely washed out of the system. CNN, Daily Kos, and the Economist are among the many organizations that have moved away from polls of all adults in favor of polls of registered voters. In theory, such a polling shift should have been beneficial to Republicans, since Republican voting groups have a higher voter registration rate than Democratic voting groups.
It remains to be seen if Democrats will be able to maintain their narrow advantage when polls inevitably shift from “registered voters” to “likely voters.”
Some pollsters, of course, most notably Rasmussen, have been employing “likely voter” screens all along, which helps account for their relatively high showings for Republicans across the board. But Chris is absolutely right: the longer polls remain stable, the more likely they are relatively accurate predictors of what will happen in November.