  Recent surveys have shown that an increasing portion of the US public
believes the two major US parties adequately represent the US public opinion
and think additional parties are needed. However, there are high barriers for
third parties in political elections. In this paper, we aim to address two
questions: "How well do the two major US parties represent the public's
ideology?" and "Does a more-than-two-party system better represent the ideology
of the public?". To address these questions, we utilize the American National
Election Studies Time series dataset. We perform unsupervised clustering with
Gaussian Mixture Model method on this dataset. When clustered into two
clusters, we find a large centrist cluster and a small right-wing cluster. The
Democratic Party's position (estimated using the mean position of the
individuals self-identified with the parties) is similar to that of the
centrist cluster, and the Republican Party's position is between the two
clusters. We investigate if more than two parties represent the population
better by comparing the Akaike Information Criteria for clustering results of
the various number of clusters. We find that additional clusters give a better
representation of the data, even after penalizing for the additional
parameters. This suggests a multiparty system represents of the ideology of the
public better.
