Why preferential voting is still the best way to elect

The system of preferential voting has come under renewed scrutiny ahead of the South Australian state election this coming weekend, with debate intensifying over whether Australia should retain the system or return to first past the post (FPTP).

Preferential voting will be used to elect members for all 47 single-member lower house seats at the Festival State’s upcoming poll, mirroring the system used for federal House of Representatives elections. Under this well-known system, voters rank candidates in order of preference, and votes are redistributed until one candidate achieves a majority. In contrast, FPTP awards victory to the candidate with the highest number of votes, regardless of whether they secure more than 50%.

Some Australian conservatives have argued for a return to FPTP, particularly following Labor’s comprehensive victory at last year’s federal election. Critics claim preferential voting amplified Labor’s result, giving the party a disproportionate share of seats.

At the 2025 election, national primary votes were 34.6% for Labor, 31.8% for the Coalition, 12.2% for the Greens, 6.4% for One Nation and 15.0% for all other candidates. After the distribution of preferences, Labor won the two-party vote by 55.2% to 44.8% and secured 94 of the 150 House of Representatives seats, representing 63% of the chamber. In both two-party margin and seat share, the result marked Labor’s largest victory since 1943.

Despite the expansion of its margin after preferences, Labor led the national primary vote by 2.8%. Election analyst Kevin Bonham said that on primary votes alone or FPTP, Labor would likely have won 86 seats compared with 57 for the Coalition, rather than the final tally of 94 to 43. He noted Labor’s vote was more efficiently distributed across electorates.

Observers point out that disproportionate seat outcomes can occur in any single-member electoral system, particularly in landslide outcomes. Some analysts argue that those concerned about large parliamentary majorities should consider advocating proportional representation rather than FPTP.

International comparisons have also been cited in the debate. The United Kingdom’s 2024 general election, conducted under FPTP, saw Sir Keir Starmer’s Labour win 411 of the 650 seats – ironically also 63% of the total – on 33.7% of the national vote. The result reflected Labour’s substantial lead in vote share over the second-placed Conservatives.

Australia’s preferential voting system dates back more than a century. Prior to 1918, federal elections were conducted under FPTP. A byelection that year in the Western Australian seat of Swan highlighted the potential impact of vote splitting between conservative parties. Labor won the contest with 34.4% of the vote, ahead of the Country Party on 31.4% and the Nationalists on 29.6%, despite the combined conservative vote reaching 61.0%.

In response, the Nationalist government introduced preferential voting later in 1918. At the subsequent Corangamite byelection in Victoria, Labor led the primary vote but lost after preferences were distributed, illustrating the system’s immediate effect. Preferential voting was originally designed to allow the two conservative parties – now the Liberals National Coalition – to compete without splitting their support.

For much of the century, preferences had limited influence because the combined primary vote for the major parties remained close to 90%. However, periods of party fragmentation and the emergence of minor parties occasionally shifted outcomes. The Democratic Labor Party, formed after a Labor split in 1955, directed preferences to the Coalition and contributed to its extended period in government from 1949 to 1972, when Gough Whitlam broke the streak.

Since the late 1980s, overall preference flows have tended to favour Labor, with support from parties such as the Australian Democrats and later, the Greens. In several elections since – including 1987, 2010 and 2022 – Labor was able to overcome primary vote deficits to win the two-party preferred vote after preferences were counted.

Supporters of preferential voting argue it allows voters to express genuine first choices without fear of wasting their vote. They also contend it better reflects parliamentary realities, where majority support is typically required to form government.

The 2025 federal contest in the Queensland seat of Dickson, held by then Opposition Leader Peter Dutton, has been cited as an example. Labor candidate Ali France won by 56.0% to 44.0% after preferences were distributed. On primary votes, however, Dutton led with 34.7% compared with France’s 33.6%, alongside significant support for a teal independent, the Greens and One Nation.

Advocates say such results demonstrate how preferential voting can account for broader voter sentiment across multiple candidates. Under FPTP, voters may feel pressured to vote tactically for a major party rather than supporting their preferred candidate.

Debate over Australia’s electoral system is likely to continue as party dynamics evolve and minor party support grows. With some recent polling suggesting One Nation could challenge the Coalition for second place in parts of the country, analysts say future preference flows could again reshape electoral outcomes at the federal level.