The current situation in this country does not support a third party. People who are ignorant talk about the "duopoly" when the fact that it exists is precisely because of the polarization in this nation. There are literally hundreds of policies and proposals by the Democrats that are an antithesis to our form of government and the beliefs of the average American. To a lesser extent, the Republicans hold a few views that also run counter to the best interests of the people. That is why elections have come down to a choice of the lesser of two evils. I believe that few of your average voters agree with everything pushed by one party or the other.
Personally, I am a conservative, but I hold some views that conservatives do not and often call me a liberal, because liberals have cornered the market in those areas. When it comes to the topic of education, I tend to the middle ground. I do not support the efforts of liberals in the teacher's unions trying to influence curriculum because when I was teaching, that was unheard of. I strongly oppose conservative efforts to defund public education to provide vouchers because of all the inherent abuses and inequities in their programs.