The Hill just became the most recent news outlet to find, through polling, that most voters want a viable third party as an alternative to the Republicans and Democrats. Their poll found that 54 percent of likely voters in 10 swing districts think there should be a third party. Their results mirror national polling from CNN (PDF) and Gallup, both of which also show majority support for a third party.

If you are thinking, “Why don’t we already have a viable third party if there really is so much demand for one?” the answer is that we have systematically structured our democracy to discourage one from gaining power. The number of viable political parties in a democracy is determined significantly by the design of its electoral system. Our election laws inherently push us toward a two-party equilibrium, but looking at other democracies, it does not need to be this way.

Most people think of a viable third party as one that can fit right down the middle, taking votes equally from each side, either because it is some theoretical perfect moderate party, or because it combines some more traditional conservative stances (like less regulation) with left-leaning policies (like support for reproductive choice and gay marriage). The problem is, it is impossible to perfectly split the difference. Any third party, be it far right, far left or an attempt a pure center, will almost always draw slightly more votes from one of the major parties than from the other, thus ending up the spoiler. Given that it is impossible to truly split the center, any third party that gets a significant share of the vote in our system will almost always end up putting the major party most opposed to their policies in power. That is what makes supporting a third party so unattractive under our system.

The Florida Senate race is a great example of this. Gov. Charlie Crist a former moderate Republican who left the party because it moved too far to the right to support him, is about as close as you can get to a candidate that could try to run straight down the middle. Yet, while Crist is polling very well (as far as independent candidates go), he is drawing more of the left-of-center vote than the right of center vote. He has split the left side with Democrat Kendrick Meek, allowing Republican Marco Rubio to gain a plurality with just the right-leaning votes. According to a Public Policy Polling [PPP] poll, the race stands at Rubio 44 percent, Crist 33 percent, and Meek 21 percent.

But if we used a different system instead of single-plurality-winner elections, this wouldn’t happen. The spoiler problem could be mitigated if we used “instant runoff” voting, which allows voters to indicate their second choice if their first choice ends up with the fewest votes. PPP actually shows us what would happen if Florida had instant runoff voting. Meek’s supporters second choice would overwhelmingly be Crist. In a head-to-head match up, Rubio and Crist each garner 46 percent. Instant runoff voting would allow voters to feel safe in voting for either of two left-leaning candidates without the consequence of helping put a Republican in power.

We know that other democracies use other electoral systems –like instant runoff voting, as well as traditional runoff elections and proportional representation– that make it easy to have several viable political parties. Systems where you can normally vote for your preferred smaller party without it greatly empowering your least favorite party. The reason we don’t have a third choice isn’t due to a lack of popular desire or need, but due to a system rigged to make it almost impossible to create a viable third party.