Two-party system
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.
List of third party performances in United States presidential elections
Occasionally, a third party becomes one of the two major parties through a presidential election (the last time it happened was in 1856, when the Republicans supplanted the Whigs, who had withered and endorsed the ticket of the American Party): such an election is called a realigning election, as it causes a realignment in the party system; according to scholars, there have been six party systems so far. Only once one of the two major parties came third in an election, but that did not cause a realignment (in 1912 the Progressive Party surpassed the Republicans, but the party quickly disappeared and the Republicans re-gained their major party status).