Democrats had near 60% in both houses. With jellyspined RINOs still in like Olympia Snowe, Susan Collins, Lisa Murkowski and more, the Democrats could have broken just about any filibuster they wanted to, if they moved in lockstep. But they didn't. Once they gained control in 06, the Democrat party started turning on itself. There were just as many Democrats against just about any given issue as there were for it, even on signature Obama issues. Really, between 06 and 10, the republicans were pretty much a non-factor.
Added at: 13:14
I'll have you know voting Libertarian is a perfectly cromulent option.