I don’t agree with your premise or whatever it is you’re trying to accomplish here. If you take points #1-4, that actually encompasses a huge array of public opinions in this country. #1: party politics; the Democrats and Republicans in govt are the same in terms of how they operate and what they really want (as many political offices as possible) the opinions that each party represent are fairly diverse.
#2: special interests; well, there’s all sorts of special interest groups out there. The NRA is the biggest one but there are large political interest groups that cover a wide range of issues, including the AARP, ExxonMobil, gay rights, PETA, the auto industry and the American Bar Association. They all get attention from politicians and have sway over them to varying extents.
#3: mainstream news media; in many ways the mainstream news media fails miserably at covering what’s really important in the world and in the country without some sort of slant. That slant is viewership/ratings/readers. They all want it and they get it by giving US what WE want. So I’d think that any major news media outlet that prospers while dishing out biased news of some sort is really only giving us what we want anyways. Since both FoxNews and CNN seem to dominate news media and their “opinions” seem to be pretty different, I’d say they also represent a wide range of political opinion and choice. Not only that, with the proliferation of the Internet, anyone can find any news media source that tells them exactly what they want to hear about any relevant political topic within a few seconds.
#4: academia; academia represents a wide, wide range of opinions and ideas. It’s infinite, really. Professors at universities hold diverse opinions. Most that do consider themselves liberal consider themselves as such in a traditional sense and not within the American liberal/conservative spectrum that has become so distorted today. There are many liberal professors at universities and there are many conservative ones and there even more that fall in between. Some professors are actually quite apolitical as well. So depending on who has influenced you throughout your academic career and what area you studied in, you could end up influenced by any number of politically-slanted people. And that’s if you’re influenced by them at all. Some people go to college and are bombarded with liberalism and they turn sour to it and become very conservative.
So I wouldn’t call these four entities the main culprits in the infestation of minority opinion in American politics that unfairly decides for us who leads us. You left out the one entity/group that DOES have an unwieldy, large influence over who becomes part of the ruling class: the rich.
The rich are the ones who have the most sway over the direction of political campaigns and the agenda of the two parties. The rich are the ones who have the most influence on special interest groups and the rich are the ones who can afford to bankroll or make large cash contributions to specific super PACs as well. The rich are the ones who own mainstream news sources, and as such have the most influence over the final decision regarding content.