 to challenge a large dominant party and, in so doing, gain political clout in the legislature. Second, voters learn, over time, not to vote for candidates outside of one of the two large parties since their votes for third party candidates are usually ineffectual. As a result, weaker parties are eliminated by voters over time. Duverger pointed to statistics and tactics to suggest that voters tended to gravitate towards one of the two main parties, a phenomenon which he called polarization, and tend to shun third parties. For example, some analysts suggest that the Electoral College system in the United States, by favoring a system of winner–takes–all in presidential elections, is a structural choice favoring only two major parties.
Gary Cox suggested that America's two-party system was highly related with economic prosperity in the country:
The bounty of the American economy, the fluidity of American society, the remarkable unity of the American people, and, most important, the success of the American experiment have all mitigated against the emergence of large dissenting groups that would seek satisfaction of their special needs through the formation of political parties.—Cox, according to George Edwards
An effort in 2012 by centrist groups to promote ballot access by Third Party candidates called Americans Elect spent $15 million to get ballot access but failed to elect any candidates. The lack of choice in a two-party model in politics has often been compared to the variety of choices in the marketplace.
Politics has lagged our social and business evolution ... There are 30 brands of Pringles in our local grocery store. How is it that Americans have so much selection for potato chips and only two brands — and not very good ones — for political parties?—Scott Ehredt of the Centrist Alliance
Third parties, meaning a party other than one of the two dominant parties, are possible in two-party systems, but they are often unlikely to exert much influence by gaining control of legislatures or by winning elections. While there are occasional opinions in the media expressed about the possibility of third parties emerging in the United States, for example, political insiders such as the 1980 presidential candidate John Anderson think the chances of one appearing in the early twenty-first century is remote. A report in The Guardian suggested that American politics has been "stuck in a two-way fight between Republicans and Democrats" since the Civil War, and that third-party runs had little meaningful success.
Third parties in a two-party system can be:
- built around a particular ideology or interest group
- split off from one of the major parties or
- focused on a charismatic individual.
When third parties are built around an ideology which is at odds with the majority mindset, many members belong to such a party not for the purpose of expecting electoral success but rather for personal or psychological reasons. In the U.S., third parties include older ones such as the Libertarian Party and the Green Party and newer ones such as the Pirate Party. Many believe that third parties don't affect American politics by winning elections, but they can act as "spoilers" by taking votes from one of the two major parties. They act like barometers of change in the political mood since they push the major parties to consider their demands. An analysis in New York Magazine by Ryan Lizza in 2006 suggested that third parties arose from time to time in the nineteenth century around single-issue movements such as abolition, women's suffrage, and the direct election of senators, but were less prominent in the twentieth century.
A so-called third party in the United Kingdom are the Liberal Democrats. In the 2010 election, the Liberal Democrats received 23% of the votes but only 9% of the seats in the House of Commons. While electoral results do not necessarily translate into legislative seats, the Liberal Democrats can exert influence if there is a situation such as a hung parliament. In this instance, neither of the two main parties (at present, 