The US really needs a legitimate 3rd political party.

I think part of it has to do with the overall situation over the last 18+ years.

Basically there are a lot of people who do not like the Republican party, but they feel in order to defeat the Democrats they have to vote Republican anyway. The TEA Party is a great example of this. They probably do have enough people to at least make a strong enough run to get a percentage of the vote large enough to secure Federal money for the next election. However, they are mostly Republicans and therefore are only going to go against the Republican Party somewhat.

I think for the last 20+- years people have felt Democrats have been making the government too big. Additionally people felt GW Bush greatly expanded it as well, which he did.

I think until people feel like there is a real possibility of a 3rd Party being victorious, they will not join en masse.