Rule of three: the growing relevance of three-candidate-preferred voting counts in Australian elections

As support for Australia’s major parties has declined, preferences play an increased role in deciding who wins each electoral contest. Small shifts in vote shares can produce significant changes in results, and a candidate’s chance of winning can depend more on the split of opposing candidate s’ vote shares rather than their own vote share. There have been an increasing number of examples from the 2022 and 2025 federal elections, along with state and territory elections, of single-member contests where the order of exclusion of candidates can decide who wins, rather than a simple tallying up of which of the top two candidates poll a higher vote after the distribution of preferences.