Editing Two-party system (section)

===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.