<P> The United States has become essentially a two - party system, since a conservative (such as the Republican Party) and liberal (such as the Democratic Party) party has usually been the status quo within American politics . The first parties were called Federalist and Republican, followed by a brief period of Republican dominance before a split occurred between National Republicans and Democratic Republicans . The former became the Whig Party and the latter became the Democratic Party . The Whigs survived only for two decades before they split over the spread of slavery, those opposed becoming members of the new Republican Party, as did anti-slavery members of the Democratic Party . Third parties (such as the Libertarian Party) often receive little support and are very rarely the victors in elections . Despite this, there have been several examples of third parties siphoning votes from major parties that were expected to win (such as Theodore Roosevelt in the election of 1912 and George Wallace in the election of 1968). As third party movements have learned, the Electoral College's requirement of a nationally distributed majority makes it difficult for third parties to succeed . Thus, such parties rarely win many electoral votes, although their popular support within a state may tip it toward one party or the other . Wallace had weak support outside the South . More generally, parties with a broad base of support across regions or among economic and other interest groups, have a great chance of winning the necessary plurality in the U.S.'s largely single - member district, winner - take - all elections . The tremendous land area and large population of the country are formidable challenges to political parties with a narrow appeal . </P> <P> The UK political system, while technically a multi-party system, has functioned generally as a two - party (sometimes called a "two - and - a-half party") system; since the 1920s the two largest political parties have been the Conservative Party and the Labour Party . Before the Labour Party rose in British politics the Liberal Party was the other major political party along with the Conservatives . Though coalition and minority governments have been an occasional feature of parliamentary politics, the first - past - the - post electoral system used for general elections tends to maintain the dominance of these two parties, though each has in the past century relied upon a third party to deliver a working majority in Parliament . (A plurality voting system usually leads to a two - party system, a relationship described by Maurice Duverger and known as Duverger's Law .) There are also numerous other parties that hold or have held a number of seats in Parliament . </P> <P> Multi-party systems are systems in which more than two parties are represented and elected to public office . </P> <P> Australia, Canada, Nepal, Pakistan, India, Ireland, United Kingdom and Norway are examples of countries with two strong parties and additional smaller parties that have also obtained representation . The smaller or "third" parties may hold the balance of power in a parliamentary system, and thus may be invited to form a part of a coalition government together with one of the larger parties, or may provide a supply and confidence agreement to the government; or may instead act independently from the dominant parties . </P>

How are parties organized at the state level