Editing Two-party system (section)

==Australia==
{{Main|Political parties of Australia|Two-party-preferred vote}}

===House of Representatives===

Since the 1920s, the [[Australian House of Representatives]] (and thus the [[Federal government of Australia|federal government]]) has in effect been a two-party system.

Since the end of [[World War II]], Australia's House of Representatives has been dominated by two factions:
* the centre-left [[Australian Labor Party]]
* the centre-right [[Coalition (Australia)|Coalition]].

The Coalition has been in government about two-thirds of time, broken by four periods of Labor governments: 1972–1975, 1983–1996, 2007–2013, and since 2022.

The ALP is Australia's largest and oldest continuing political party, formed in 1891 from the [[Australian labour movement]]. The party has branches in every state and territory.

The Coalition refers to the alliance between the [[Liberal Party of Australia]] (Australia's 2nd largest party) and [[National Party of Australia]] (4th largest). It was formed after the [[1922 Australian federal election]], when the [[Nationalist Party (Australia)|Nationalist Party]] (ancestor of today's Liberal Party) lost its absolute majority, and was only able to remain in government by allying with the Country Party (now called the [[National Party of Australia|National Party]]). Under the Coalition agreement, if the Coalition forms government then the [[Prime Minister of Australia|Prime Minister]] will be the leader of the Liberals, and the [[Deputy Prime Minister of Australia|Deputy Prime Minister]] will be the leader of the Nationals. In theory, disagreements between the Coalition's constituent parties would lead to the Coalition splitting apart. This has happened only a few times in Australia's modern political history, and has always resulted in the Coalition coming back together by the next election. The most recent split occured in 2025, following [[2025 Australian federal election|Labor's landslide victory]] at that year's election.<ref>https://www.abc.net.au/news/2025-05-20/nationals-will-not-re-enter-coalition-agreement/105313818</ref><ref>https://www.theguardian.com/australia-news/2025/may/20/nationals-leaving-split-coalition-liberal-party-australian-election></ref><ref>https://theconversation.com/nationals-break-the-coalition-in-a-major-blow-to-sussan-ley-256455</ref>

One reason for Australia's two-party system is because the House of Representatives (which chooses the [[Prime Minister of Australia]]) is elected through the [[instant-runoff voting]] electoral system. Although voters can preference third parties and independents above the major parties, and the voting method has a reduced [[spoiler effect]], there is still only one member per electoral division (ie: a winner-take-all system) and so major parties tend to win the vast majority of seats even if they need to rely on preferences to do so. For example, a Labor candidate may win a seat with 30% of the vote for Labor and 21% from [[Australian Greens]] voters who ranked Labor second.

===Senate===

On the other hand, the [[Australian Senate]] is effectively a multi-party system, and a Senate majority matching the House is very rare. It uses [[single transferable vote]] with multiple Senators for each state/territory. This results in rough [[proportional representation]] and as a result, third parties have much more influence and often hold the [[Balance of power (parliament)|balance of power]]. Since 2004, the [[Australian Greens]] have been the third largest party in the country, with 8-13% of the national vote and an equivalent amount of Senators. Prior to this, the [[Australian Democrats]] was the third largest party. Other current and past parties include [[One Nation (Australia)|One Nation]], the [[Liberal Democratic Party (Australia)|Liberal Democrats]] and [[Family First Party|Family First]].

Some Australian states have seen the rise of minor parties at either the state or federal level (eg: [[Centre Alliance]] in [[South Australia]], [[Katter's Australian Party]] in northern [[Queensland]], and the [[Shooters, Fishers and Farmers Party]] in western New South Wales), while some have seen long periods of dominance by one party. Some parties are absent entirely in parts of the country.
* The [[Australian Capital Territory]] has had a [[Australian Labor Party (Australian Capital Territory Branch)|Labor]]/[[ACT Greens|Greens]] coalition government since 2012, opposed by the [[Liberal Party of Australia (A.C.T. Division)|Liberals]] (Nationals not present). Labor was in government alone from 2001-2012.
** Notably, the ACT is the only state/territory where the Greens have been in power.
* In the [[Northern Territory]], the two main parties are [[Australian Labor Party (Northern Territory Branch)|Labor]] and the [[Country Liberal Party]] (CLP), which aligns with the Coalition at the federal level.
* In [[Western Australia]], the [[Liberal Party of Australia (Western Australian Division)|Liberal]] and [[National Party of Australia (WA)|National parties]] are not in a permanent coalition at the state level. At the [[2021 Western Australian state election]] [[Australian Labor Party (Western Australian Branch)|Labor]] won 53 out of 59 lower house seats in a landslide victory. The National Party won 4 seats making them the official opposition. The Liberals won only 2 seats, putting them on the [[crossbench]].
* In [[New South Wales]] and [[Victoria (Australia)|Victoria]], the main parties reflect the situation nationally: Labor versus the Coalition of the Liberals and Nationals. NSW is the only state where the Coalition has never split, but has also never merged into one party.
* In [[South Australia]] and [[Tasmania]], the main parties are Labor and the Liberals, with the Nationals not holding any seats.
* In [[Queensland]], the main parties are [[Australian Labor Party (Queensland Branch)|Labor]] and the [[Liberal National Party of Queensland|Liberal-National Party]] (LNP). Historically, the Country Party was the largest Coalition member and they governed the state from 1957 until 1989. This was partially due to a [[malapportionment]] which heavily favoured rural seats. It had been originally designed by a Labor government, but ended up benefitting the Country Party as demographics shifted. Later, Premier [[Joh Bjelke-Petersen]] increased his power by using [[Queensland Police]] to suppress political dissent, and enacted the [[Bjelkemander]], worsening malapportionment in order to reduce the power of the Liberals so his Country Party could rule alone. Eventually, media reports and the [[Fitzgerald Inquiry]] revealed wide-ranging corruption police and government. Bjelke-Petersen was forced to resign in disgrace, while many high-ranking police and politicians were criminally charged. Labor has been in power for most of the time since then, with the state Country and Liberal parties merging into the LNP, which is a member of the Coalition federally.