Gallup reports today that Democratic support has shrunken to the same levels seen in the second quarter of 2005, meaning the gains in national support the Democratic Party saw during the last years of the Bush administration have essentially disappeared. Here's how Democratic support has shrunken since the post-election Democratic euphoria early last year:

And how yearly averages have changed since 2003:
These numbers include Democratic and Republican-leaning independents, so what we're talking about here is not the same as party ID, and, as much as anything else, these trends indicate that independents swing hard toward the Democratic party over the last years of the Bush administration and are now trending back away from that.

In the fourth quarter of '09, Democrats still hold a 33 to 27 percent party ID advantage over Republicans, but more independents lean Democratic than Republican: 14.2 percent lean Democratic, 8.4 percent don't lean, and 15.2 percent lean Republican.