Why third place matters
How the third-placed candidate’s preferences now decide more Australian seats than ever
By Ben Raue, Electoral analyst
Australia’s voting rules have barely changed, but its contests have. Ben Raue shows how the falling major party vote has made preferences decisive: Labor and the Coalition took over 97% of the primary vote in 1951 and 1954, but just 66.4% in 2025, and only eleven seats were won on primary votes alone at that election.
As more of the vote sits with candidates outside the top two, the third-placed candidate’s preferences can decide who wins. A party with no hope of winning can settle a seat from third place, and lose that power if it makes the top two. With One Nation polling strongly, close three-way races are likely to become more common, making results slower to call and harder for voters to predict.
The full report · 18 pages, with every chart.
Get the full reportWhat we found
1. Two thirds of seats now go to a full preference count
In 1987 over 60% of seats were decided without preferences; in 2022 just fifteen were won on primary votes, and in 2025 just eleven. In 2004 almost three quarters of seats were settled before the final preference round, but in 2022 and 2025 over two thirds needed a full distribution. The share of the vote held by the third-placed candidate, with three left in the count, rose from just over 10% in 2004 to over 19% in 2025.
2. Greens and One Nation preferences have hardened in opposite directions
Less than 70% of Greens voters preferred Labor over the Coalition in the early 1990s; in 2025 it was 88.2%. One Nation preferences were close to 50/50 up to 2016, but since 2019 have leaned clearly to the Coalition, with 74.5% of One Nation voters preferencing it over Labor in 2025.
3. Liberal how-to-vote cards can decide Labor–Greens contests
Many Liberal voters follow their party’s card when choosing between Labor and the Greens, and Liberal preferences helped Adam Bandt win Melbourne in 2010. In the Queensland seat of South Brisbane, the LNP switched to preferencing the Greens in 2020, the share of its preferences flowing to Labor fell from 62% in 2017 to 36%, and deputy premier Jackie Trad lost her seat to the Greens. When the LNP switched back in 2024, the flow rose to 73%.
4. The order of second and third can matter more than the primary vote
In Macnamara in 2022, Labor, the Greens and the Liberals all polled between 29% and 31.8% on the primary vote; the Greens finished third by 0.7% once minor candidates’ preferences were counted, their preferences flowed to Labor, and Labor won comfortably. In 2025 the Greens won Ryan but lost Griffith, despite a higher primary vote in Griffith, because Labor preferences carried them in one and LNP preferences beat them in the other.
What’s in the report
- Introduction p. 3
- Preferences in the two-party era p. 4
- Influence of third-place preferences p. 9
- Changing preferences and how-to-votes p. 12
- When second and third are close p. 15
- Implications for voters and poll watchers p. 17
How we counted
The brief draws on federal election results: the combined major party primary vote, seats won on primary votes, seats won by a candidate who trailed on the primary vote, non-classic contests, and the share of the vote held by the third-placed candidate in the three-candidate-preferred count. It tracks how minor party preferences split between Labor and the Coalition at each election, uses the state seat of South Brisbane (2017–2024) to show the effect of how-to-vote cards, and plots the twenty Labor–Liberal–One Nation contests at the 2026 South Australian election by three-candidate-preferred vote, shaded for the likely winner on average preference flows.
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