Senate preferences playing a bigger role

Yesterday’s final result in New South Wales was a bit of a surprise, with One Nation closing a primary vote margin of 0.21 quotas. Even after One Nation won another senator in Western Australia on Thursday afternoon, the gain they had made in WA wouldn’t have been another to do the same in NSW.

Antony Green previously produced a table showing how the switch from group voting tickets had meant that nearly all Senate elections resulted in the candidate leading on the primary vote ended up winning. I’ve now extended this table to show the 2025 results.

A majority of seats that weren’t won on a full quota in 2013 ended up being won by a party that was trailing on the primary vote, but it didn’t happen once in 2019. The only case in 2022 was David Pocock in the ACT, so the two One Nation gains in 2025 are the only cases in a six-seat Senate race under the current post-GVT electoral system. I should note that for most of this blog post I’m just looking at the six state contests, not the territories, which have a different dynamic.

So, why did this happen?

The first thing worth noting is that there has been a change in the make-up of the primary vote, particularly amongst parties on the right. The Coalition’s primary vote dropped by 4.35% nationally. That’s more than a quarter of a quota, and can make the difference between the third Coalition candidate being competitive and not competitive in a number of states.

One Nation’s primary vote has also picked up by 1.38%, which is a help in getting them closer to winning a seat. This vote has undoubtedly come in part from the Coalition, or from other right-wing parties like Trumpet of Patriots who fell a long way short of the 2022 UAP vote. But there are also numerous other right-wing minor parties that are sources for preferences for One Nation. In practice, in most states One Nation were the only viable right-wing prospect for a third right-wing seat.

In a number of states, this dynamic created the space for Labor to win a seat that would normally go to the right. They did this in two states, and came close to doing it in three other states.

But I think there’s also reason to think that One Nation has benefited from stronger preference flows than in the past.

I made an attempt to estimate the number of preferences marked by each voter. It’s made a bit hard because some voters marked above and below the line preferences, and only one set of preferences counted as formal, but there is an increasing number of voters marking 7 or more preferences.

It’s also worth bearing in mind that the number of Senate groups have been dropping, so you need to number less boxes to cover a high proportion of the groups competing in the Senate race.

There has also been a reduction in the number of votes that exhaust by the end of the count. This is a bit of a difficult measure to use because particular votes can end up exhausting or not depending on the exact make-up of the vote in a particular race. But the drop is pretty significant: from 7.3% in 2019, to 6.3% in 2022, to 5.2% in 2025.

So with more preferencing and a smaller ballot, you’d expect parties to need a bigger share of a quota to win the last seat, and more potential for a runner-up candidate to catch up and win.

It’s also worth noting that One Nation has a lot of experience being the runner-up in Senate races.

Of 18 six-seat Senate contests since the introduction of the post-GVT electoral system, One Nation have been seventh on primary votes in thirteen of those contests. This doesn’t include the three Queensland contests where One Nation was fifth or sixth on the primary vote. The only cases where One Nation was further away from winning were in Tasmania this year, when they came eighth, and Victoria in 2022, when United Australia outpolled One Nation and became the main right-wing minor party.

This table shows 12 of those contests, excluding Victoria in 2019 when Derryn Hinch overtook One Nation.

One Nation hasn’t always done great on preferences, but there is a bit of a trend. One Nation doesn’t do great when they’re head to head with the Greens or the Lambie Network.

But they do particularly well against Labor. The two seats they gained in 2025 had the best preference flows, but they also gained ground against Labor in Victoria and South Australia this year, and Western Australia in 2022. Those were all cases where the Coalition vote collapsed and Labor gained a 4-2 split.

I know that there will be plenty on the left who will be disturbed by One Nation winning a bigger share of seats, but to be honest it doesn’t have much to do with the progressive side of politics. One Nation’s success has been mainly driven by the collapse of the Coalition and reordering of votes amongst the right-wing minor parties. The Senate system naturally defaults to 3-3 splits, and a better-organised right-wing minor party has the potential to develop a similar niche to the Greens.

But if the ballot paper is getting smaller and clearer, that’s not a bad thing. It’s also not a bad thing if voters are naturally choosing to fill out more preferences, perhaps aided by a more legible ballot paper.

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