The problem is that third parties do not represent the majority of the country and likely a minority of any given area.
That's not the problem. Neither do the other two parties and they do fine.
I used to think the problem with third parties was that they do not run for local offices and only focus on national offices unlesd it is a plant designed to siphon votes from a particular canditate in order to let a less desirable one get elected. But after looking around a bit, i have concluded that the honest reality is that third parties simply do not have much support. I tend to disagree with less on issues from a candidate with a big party than i disagree with on with the closest counter part third party. Many people feel the same at least on a local level and a third party is a waste on the national level because they will have to either caucus with a big party or fight both of them and end up being ignored.
Third parties simply are not big tent parties and are likely better off running as one of the big parties through the primary process. An example of this is the tea parties (yes, there are more than one).
Now if you disagree, before replying, think about how the tea party republicans have been treated and explain how any third party trying to do something without even partial support of a big party would do any better.
The problem is that you're (and the rest of us) voting for the two candidates that the "Lesters" have picked for us to vote on. The game is rigged.