The political party element is an essential feature of the US capitalism that substantially contributes to its suckiness. There is no such thing as market capitalism, only a bunch of money grubbers with different amounts of political power. In some countries (like Scandinavia or even Western Europe) that power is balanced by broader societal interests, in other countries (like the US) it usually trumps all other societal interests. This balancing of money grubber power is determined, for the most part, by a country's political institution makeup, and electoral laws and the political culture are a big chunk of that makeup.
Anti-institutionalism and focus on individual celebrities/demagogues has been a defining feature of the US politics since the times of Alexis deTocqueville, if not earlier. This is precisely what makes the US brand of capitalism suck - it generates pompous political rhetoric, appealing to the lowest common denominator, while hiding the tyranny of the wealthy under a façade of the majority rule.
The main problem of the US political-economic system is that the personal trumps the social. This allows a small group of oligarchs to hold to enormous power by paying off the devil when necessary and crafting a democratic spectacle and other circuses for the pious yet ignorant masses (the 77% that believe in hell, angels and biblical quotations prominently displayed in public places).
Change that, and you will have a Scandinavia on this side of the pond, or at least a Canada extending to the Rio Grande/Gulf of Mexico.
Wojtek