It's gotta be more complicated than that. The "capital" is not an unified, omniscient force - in fact, there is no such a thing as capital, only individual money grubbers and their obedient servants in the governemtn, the media, and the academe. So it makes a whole lot of a difference *which* capitalists are supported by *what* political party and *where.* That is the essence of that old US political landmark knows as machine politics and political patronage.
An even more important point is that much of today's politics, especially in the symbolic realm, is driven by the ascent of the middle class, whose class identity can be succintly described as 'responsibility toward above, authority toward below." Most middle classers aspire to the upper class status, and loath or fear lower classes. What makes you think they would support politics aimed at empowering lower classes and limiting the power of upper classes?
If anything, Dem politics are quite realistic, given the current class structure of the US society. It is a very conservative society, and it is becoming even more so as the suburbs grow and the acedeme sells middle class credentials right and left.
wojtek