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.
Minor party
In the United States they are often described as third parties. Minor parties in the U.S. include the Libertarian Party, the Green Party, Constitution Party, and others that have less influence than the major parties. Since the American Civil War (1861–1865), the major parties have been the Republican Party and the Democratic Party. Since 1860, six presidential candidates other than Republicans and Democrats have received over 10% of the popular vote, although one of them was a former president, Theodore Roosevelt.