Third party (United States)
In the context of the United States' political system, a third party is any political party organized in all or nearly all states other than the two current leading parties, which since the time of the American Civil War have always been the Democratic and the Republican parties.
The most significant reason for America's being a two-party system is its predominant use of a first-past-the-post voting system. In first-past-the-post, also known as winner-take-all, the person with the greatest number of votes wins, even if the margin of victory is extremely narrow or the proportion of votes received is not a majority. Unlike in proportional representation, runners-up do not gain any representation.
Because a candidate can win with a plurality, voters have a powerful incentive to vote for one of the two candidates with a chance of gaining the greatest number of votes. Hence, any third party will have a difficult time gaining a foothold. Successful third party candidates tend to either retire from office quickly (Gov. Jesse Ventura of Minnesota, Gov. Lowell Weicker of Connecticut, Gov. James Longley of Maine) or to affiliate formally Mayor John Lindsay of New York, Senator James Buckley of New York, Congressman Thomas Foglietta of Philadelphia) or informally (Congressman Bernard Sanders of Vermont) with a major political party.
A longtime Pennsylvania legislator who has been an opponent of legislative obstacles to third party ballot status, State Rep. Mark B. Cohen of Philadelphia, said "Third parties can be a vital escape valve for political energies when they put forward a bold and relevant challenge to existing party politics, but history shows that the major parties respond with candidates, programs and policies that successfully compete with the appeal of the third parties. Third parties are one of the oldest ideas in American politics that seem perenially new to their proponents."
There are other first-past-the-post countries where there are third parties, the United Kingdom, Canada, and India being examples. However, in those countries local voting strengths has enabled the third parties to successfully challenge in individual districts, to the point where they can gain voters from one of the two main parties by being the main local alternative to the other. Hence, although there are more than two parties represented in Parliament, local voters effectively only have binary choices. Many of India's small parties compete only in certain states and, similarly, it can be said that Canada no longer has any national parties (see Duverger's Law).
America's two-party system is further strengthened by the electoral college. Since the electoral college requires that a candidate have a majority of electoral votes, state parties on opposite sides of the country have to work together. Moreover, in nearly every state, electoral college votes are allocated on a winner-take-all basis. Thus, though they are occassionally able to win election to local or state office, third parties rarely win more than a small percentage of the vote in presidential elections.
Aside from the mechanics of first-past-the-post, many states use ballot access laws to keep third parties off the ballot or force them to spend the bulk of their resources just to get on the ballot. Such obstacles include the requirement in several states that third party candidates obtain thousands of signatures of registered voters in order to get their candidates listed on the ballot. Once they are on the ballot, third party candidates may not be allowed to participate in debates, and they are not likely to have as much money as the major party contenders. In many states, it is also quite difficult for any party other than the two major ones to be officially recognized by state election authorities as a legitimate political party, and they may face thresholds or other requirements that make it difficult-to-impossible for a party to retain such recognition once it is granted.
Because of the difficulties third parties face in gaining any representation, third parties tend to exist to promote a specific issue, one which either or both of the major parties may eventually end up co-opting. As a counterexample, H. Ross Perot eventually founded a third party, the Reform Party, but he apparently intended it to exist solely as a vehicle to support himself and his agenda and never intended it to field any Congressional or gubernatorial candidates.
The last third party to win electoral votes in a presidential election was the American Independent Party in 1968, though a "renegade" elector gave a vote to the Libertarian Party in 1972. The last candidate not affiliated with either of the major parties (though not yet a member of a third party) to win a major portion of the popular vote was independent Ross Perot, who won 18.87% of the popular vote in the 1992 Presidential election.
There have been few third party governors in the past few decades. The last was Jesse Ventura, a member of the Reform Party and later the Minnesota Independence Party, who governed Minnesota from 1998-2002.
The major way in which third parties can influence elections in the United States is through electoral fusion.
Notable Presidential elections
The Free Soil Party, advocating stopping the spread of slavery into the lands acquired from Mexico during the Mexican War, nominates former President Martin van Buren for President. Van Buren wins 10% of the vote, helping swing the election to Zachary Taylor.
The Republican Party, barely two years old, runs a strong campaign for the Presidency, its nominee [[John C. Fr�mont]] coming second and sweeping aside the remains of the old Whig Party which had fallen apart amidst divisions on slavery.
Abraham Lincoln is elected president, causing the formerly third party Republicans to permanently supplant the Whigs as one of the nation's two major parties. The Republican Party is considered to have been the most successful third-party movement in United States history.
Republican Theodore Roosevelt runs on a Progressive Party ticket in the 1912 election and garners more votes than Republican incumbent William Howard Taft. The split in the Republican vote propels Democrat Woodrow Wilson to victory with 42% of the popular vote, but 435 electoral votes.
Strom Thurmond runs on the segregationist Dixiecrat Party ticket in the 1948 election, splitting the Democratic vote and winning 39 (all Southern) votes in the electoral college. Former Vice President and Cabinet Member Henry Wallace also challenges for Democrat votes by running for the Progressive Party and receiving 2.4% of the popular vote, though no votes in the electoral college. Despite both challenges Truman still defeats Dewey.
George Wallace of the American Independent Party runs in the 1968 election. Wallace captures 13% of the popular vote, receiving 46 electoral votes in the South as well as many votes in the North. Republican Richard Nixon wins the election with 43% of the popular vote and 301 electoral votes.
Ross Perot (not affiliated with any party) wins almost 19% of the popular vote (though no electoral votes), possibly helping Democrat Bill Clinton to win the Presidential election with only a 43% plurality of votes.
In the 2000 Presidential election, George W. Bush wins the deciding state of Florida by fewer than 600 votes. Some Democrats accuse Green Party candidate Ralph Nader of having cost them the election, and in discussion of strategies for the U.S. presidential election, 2004 both parties weigh the costs to the Democrats of another Nader presidential run.
Current U.S. third parties
Various other minor parties are given in the list of political parties in the United States.