Voter defection
What the records on voter defection say about how many voters move between parties, and what moves them.
ow many voters actually switch the party they vote for between one election and the next, and what seems to drive it?
McAllister, Bean & Pietsch (2012)
A study of the 2010 federal election, using the Australian Election Study, on which voters left the party they backed in 2007 and what separated them from the ones who stayed.
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In 2010, 70% of the people who voted Labor in 2007 stayed with Labor. That was its worst retention since the Australian Election Study began in 1987. 14% went to the Coalition and 12% to the Greens.
Jackman & Mansillo (2018)
A study that tracked 400 national polls across the 2013-16 parliament, on when voter support actually moves — during the term or during the campaign.
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The Turnbull leadership change in 2015 produced one of the biggest jumps in the polling record — and the gain had halved within about four months.
Jackman and Mansillo found less movement during the formal campaign than at other points in the same parliament, which they read as the two major campaigns cancelling each other out.
Bongiorno (2026)
A public lecture on how the Australian party system was built and why its old moorings may be coming loose, drawing on decades of election-study figures.
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Accent Research, via The Conversation (2026)
An Accent Research poll of 1,002 Victorians, reported by The Conversation, on where people who voted Labor in 2022 say they are going now.
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In the August 2026 Accent poll of Victorians, 57% of 2022 Labor voters stayed with Labor, 13.4% moved to One Nation, 11% to the Coalition and 8.5% to the Greens.
ABC News (2026)
An ABC round-up of the polling for the 2026 Victorian state election, and of the three-way contest between Labor, the Coalition and One Nation.
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ANU 2022 election study
The ANU's summary of its 2022 election study, on how voters rated the leaders and how those ratings sat against the vote.
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Moffitt, via The Guardian (2026)
The Guardian’s report on the May 2026 Nepean by-election, where the Liberals held the seat against One Nation. It quotes Benjamin Moffitt estimating that 10–15% of Labor voters defected, and notes One Nation ran almost no local organisation.
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One Nation took a large share of the Labor vote at Nepean while running very little of the usual local campaign.
Synthesis
All these figures rest on what survey respondents say they did. Whether people who report switching actually switched is hard to check against the count.
It is unresolved whether poor leader ratings cause the defection or simply arrive alongside it — an unpopular leader and an unpopular government tend to be the same government.
No post-election study of individual Victorian voters exists for the 28 November 2026 contest, so the state-level flows are still inferred from polls.
How much of One Nation's current support is a lasting realignment rather than a place to park a vote is not known.
Linked notes
/notes/persuasion
/notes/preference-flows
/notes/turnout-tactics
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