There are lots of people lamenting the tendency of Blue Dogs like Mary Landrieu, Blanche Lincoln, Evan Bayh, etc. etc. of ignoring their constituents and instead, representing WellPoint or BP or some such thing, and rightly so, but there's another thing hamstringing the Left: We all work for or otherwise support our political opponents.
As I type this, I am supporting AT&T, who is trying to kill net neutrality. My U-Verse payments (or, more accurately, my landlord's U-Verse payments) go in part toward something I adamantly oppose. If you have a mortgage payment or a checking account, chances are you're supporting mounttop removal or stadium financing or illegal arms trading or a million other nefarious schemes. Most of the jobs I've had have been supportive of the other side, too, either because I was working directly for some right-wing asshole, or because my work prolonged and supported something I detest. In other words, just to earn a living and take part in the world, we lefties are forced to support our enemies. Right-wingers don't have this problem. As far as I know, there aren't any conservatives who are forced by economic conditions beyond their control to work for, say, Greenpeace or the ACLU.
So, in addition to the fact that around half of the Democratic Party are recalcitrant corporate hookers, we are supplying their pimps with capital.