The whole US system is basically an oligarchy. Here's what a recent large scale study analyzing many decades of US policy concludes:

In the United States, our findings indicate, the majority does not rule—at least not in the causal sense of actually determining policy outcomes. When a majority of citizens disagrees with economic elites or with organized interests, they generally lose. Moreover, because of the strong status quo bias built into the U.S. political system, even when fairly large majorities of Americans favor policy change, they generally do not get it.

I also recommend Democracy for the Few which is a great book discussing how US political system actually works. Any semblance of democracy is pure theatre.