Partisan style varies according to each jurisdiction, depending on how many parties there are, and how much influence each individual party has.
In a nonpartisan system, no official political parties exist, sometimes reflecting legal restrictions on political parties. In nonpartisan elections, each candidate is eligible for office on his or her own merits. In nonpartisan legislatures, there are no typically formal party alignments within the legislature. The administration of George Washington and the first few sessions of the United States Congress were nonpartisan. Washington also warned against political parties during his Farewell Address. In the United States, the unicameral legislature of Nebraska is nonpartisan but is elected and often votes on informal party lines. In Canada, the territorial legislatures of the Northwest Territories and Nunavut are nonpartisan.
In New Zealand, Tokelau has a nonpartisan parliament. Many city and county governments in the United States and Canada are nonpartisan. Nonpartisan elections and modes of governance are common outside of state institutions. Unless there are legal prohibitions against political parties, factions within nonpartisan systems often evolve into political parties.
In one-party systems, one political party is legally allowed to hold effective power. Although minor parties may sometimes be allowed, they are legally required to accept the leadership of the dominant party. This party may not always be identical to the government, although sometimes positions within the party may in fact be more important than positions within the government. North Korea and China are examples; others can be found in Fascist states, such as Nazi Germany between 1934 and 1945. The one-party system is thus often equated with dictatorships and tyranny.
In dominant-party systems, opposition parties are allowed, and there may be even a deeply established democratic tradition, but other parties are widely considered to have no real chance of gaining power. Sometimes, political, social and economic circumstances, and public opinion are the reason for others parties' failure. Sometimes, typically in countries with less of an established democratic tradition, it is possible the dominant party will remain in power by using patronage and sometimes by voting fraud. In the latter case, the definition between dominant and one-party system becomes rather blurred.
Examples of dominant party systems include the People's Action Party in Singapore, the African National Congress in South Africa, the Cambodian People's Party in Cambodia, the Liberal Democratic Party in Japan, and the National Liberation Front in Algeria. One-party dominant system also existed in Mexico with the Institutional Revolutionary Party until the 1990s, in the southern United States with the Democratic Party from the late 19th century until the 1970s, in Indonesia with the Golkar from the early 1970s until 1998.
Two-party systems are states such as Honduras, Jamaica, Malta, Ghana and the United States in which there are two political parties dominant to such an extent that electoral success under the banner of any other party is almost impossible. One right wing coalition party and one left wing coalition party is the most common ideological breakdown in such a system but in two-party states political parties are traditionally catch all parties which are ideologically broad and inclusive.
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.
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.
Multi-party systems are systems in which more than two parties are represented and elected to public office.
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.
More commonly, in cases where there are three or more parties, no one party is likely to gain power alone, and parties have to work with each other to form coalition governments. This is almost always the case in Germany on national and state level, and in most constituencies at the communal level. Furthermore, since the forming of the Republic of Iceland there has never been a government not led by a coalition, usually involving the Independence Party or the Progressive Party. A similar situation exists in the Republic of Ireland, where no one party has held power on its own since 1989.
Since then, numerous coalition governments have been formed. These coalitions have been led exclusively by either Fianna Fáil or Fine Gael.
Political change is often easier with a coalition government than in one-party or two-party dominant systems. If factions in a two-party system are in fundamental disagreement on policy goals, or even principles, they can be slow to make policy changes, which appears to be the case now in the U.S. with power split between Democrats and Republicans. Still coalition governments struggle, sometimes for years, to change policy and often fail altogether, post World War II France and Italy being prime examples. When one party in a two-party system controls all elective branches, however, policy changes can be both swift and significant. Democrats Woodrow Wilson, Franklin Roosevelt and Lyndon Johnson were beneficiaries of such fortuitous circumstances, as were Republicans as far removed in time as Abraham Lincoln and Ronald Reagan.
Barack Obama briefly had such an advantage between 2009 and 2011. As of 2017, President Donald Trump currently enjoys Republican control of both the house and senate.