The Impact on Senate Election Results of Abolishing GVTs – the Lessons for Victoria

Over the next week I will publish several posts looking at the abolition of Group Voting Tickets (GVTs) in Victoria and the implications this has for the state’s Legislative Council election in November.

Work I’ve undertaken in the past, about Senate elections both before and after the abolition of GVTs, produces clear conclusions.

Abolishing GVTs will increase the importance of first preference votes and diminish the value of preference transfers. Abolishing GVTs advantages parties that campaign for votes and disadvantages those that rely on deals and transfers to be elected.

Abolishing GVTs also ends the ability of parties to conspire and use GVTs to block the election of high polling parties. It also stops parties using GVTs to elect low-polling parties that few voters have heard of into important upper house balance of power seats.

The key aim of abolishing GVTs is to end party control over between-party preferences and leave it to voters to make the decision. With 95% of votes tied up in party tickets, too many elections had been decided by opaque preferences deals that voters had little knowledge of. A new form of above-the-line (ATL) voting was created allowing voters to show preferences for parties rather than candidates. Voters still had the option to vote below-the-line (BTL) for individual candidates of any party.

In other states this has been implemented with full optional preferential voting. A voter must indicate a first preference for a formal vote, but further preferences were optional. At elections conducted under the new rules, only a third of ATL ballot papers have preferences beyond ‘1’ and exhausted preferences have come to play a part in deciding who wins the final seats. (See my previous post that covered experience with the change in NSW.)

By contrast, the Senate instructions after the abolition of GVTs has been to mark at least six preferences, though a savings provision allows any first preference vote to remain formal. Under these instructions, around 95% of ballot papers are completed above the line (ATL) with between-party preferences. Given the exhaustion rate of preferences for minor party votes, there hasn’t been much difference between the role of preferences in the two ballot marking systems.

Abolishing GVTs makes it nearly impossible to win from a low vote AND from behind on preferences. Abolishing GVTs does not prevent a party winning from a low vote, nor prevent a trailing candidate from winning on preferences, though it does make it harder. But is becomes extremely difficult to do both at the same time.

A party winning from a low vote is possible without GVTs if there is an even split of vote between remaining parties. The United Australia Party’s Ralph Babet won a Victorian Senate seat in 2022 from only 0.28 quotas (4.0%). This was because there were five parties between 0.20 and 0.28 quotas competing for one seat. Without GVTs, preference flows were relatively weak and Babet maintained his lead to win the final seat. Preferences were not responsible for his victory.

And coming from behind is possible. In NSW at the 2025 Federal election, strong preference flows from the Coalition and small right-wing parties allowed One Nation on 0.42 quotas (6.1%) to pass Labor’s third candidate on 0.63 quotas (9.1%).

Without GVTs, the classic 2013 Victorian Senate case of Ricky Muir (Australian Motoring Enthusiasts Party) on 0.5% defeating Helen Kroger (Liberal) on 11.6% would be impossible. Muir’s election was the equivalent of a lower house candidate on 1.7% defeating a candidate with 40%.

As One Nation showed in 2025, is is possible for a candidate with two-thirds of another candidate’s vote to come from behind and win on preference transfers. Voters still have their say on preferences, but without GVTs, results can’t be engineered. Muir’s case of winning from behind with only one-23rd of the winning candidate’s vote is absolutely impossible without GVTs.

And to date, every jurisdiction except except Victoria has understood this inherent problem with GVTs and abolished them. Next week it appears Victoria will be the last to join the club.

Based on One Nation’s two come from behind Senate victories in 2025, I think around 0.4 quotas is the minimum a party needs for victory, 6.5% translated into Victorian Legislative Council numbers. That’s unless you get a case like Ralph Babet’s where a seat remains to be filled and all remaining parties have a low vote.

Looking at how many parties have been elected from trailing positions, the difference produced by the abolition of GVTs for Senate elections is clear.

At the 2013 half-Senate election, the last to use GVTs, 9 of the 36 state Senate positions were won by trailing candidates. At three half-Senate elections since the abolition of GVTs, only 2 of 108 state Senate seats have been won by trailing candidates.

And both of those trailing wins were aided by Senate instructions to mark 6 preferences. Trailing wins may be even harder under instructions for ‘1’ with further preferences optional.

How to Measure the Impact of Preferences

Upper house elections, with or without GVTs, allocate seats by proportional representation with the use of preferences to determine the final seats. Comparing preferential results to a non-preferential form of proportional representation can highlight the difference between GVT and non-GVT systems.

A similar technique is used in political science literature to compare Australia’s lower house preferential voting outcomes with those that would occur under simple majority voting. Assuming voters would vote the same under both systems, how often do preference transfers alter the simple majority result, that is elect a trailing candidate over a higher polling opponent?

To explain how I can apply this method to proportional upper house voting, I need to start with a brief and hopefully understandable detour into electoral system theory.

A Classification of Electoral Systems

Textbooks generally classify electoral systems into three broad categories –

• Single member systems
• Multi-member systems
• Hybrid systems

Hybrid systems are an amalgam of the other two types. For instance, the Mixed-Member Proportional (MMP) system used in New Zealand is a hybrid including both single and multi member elements. I won’t be discussing hybrid systems in this post.

Single member systems have two basic types. The first is simple majority voting, often misleadingly called ‘first-past the post’. (There is no winning post.) The second is what we in Australia call preferential voting, the UK calls the Alternative Vote, and is known as Rank Choice Voting or Instant Run-Off Voting in the USA.

This post is about multi-member electoral systems of which there are many variants. The following four attributes are often used to categorise multi-member systems.

1. Representation: is representation proportional or majoritarian, (Most are proportional as muti-member block voting is now rare.)
2. Candidate Choice: are party lists open (you can select candidates) or closed (you can only vote for the list).
3. Seat Allocation: are seats allocated using a divisor method such as D’Hondt and Sainte-Lague, or a fixed quota with the allocation of final seats by highest remainder.
4. Preferences: are preferences used to allocate seats.

Category 4 is the system used in Australia. Technically it is known as Proportional Representation by Single Transferrable Vote (PR-STV) and in Australia is a family of related systems.

Category 2 on candidate choice creates two sub-categories for Australian PR-STV. The Hare-Clark system used to elect the ACT Legislative Assembly and Tasmanian House of Assembly is clearly open list as votes must be cast for candidates.

The variant used for the Senate and mainland upper houses has a divided ballot paper with the overwhelming majority of electors voting ‘above-the-line’ (ATL) for party tickets, and only a small minority (<5%) voting 'below-the-line' (BTL) for candidates.

In law, and according to the counting method, the divided ballot paper used for Senate and state upper house elections is an open list system. In practice, with 90-95% of votes completed ATL, these systems operate as a closed list quota-based system of proportional representation. ATL votes cannot ‘leak’ out of a party ticket, and most BTL votes also stay within each ticket before giving preferences to candidates of other parties.

For this reason, while Senate and mainland Legislative Council elections are clearly category 4 proportional representation systems, they also operate as a variant of Category 3 quota-based highest-remainder proportional representation, or List-PR as I’ll refer to it in this post. The differences between who wins final seats under PR-STV versus List-PR highlight the impact of between-party preferences.

Comparing the two systems –

• With minimal leakage of BTL votes, there is no difference between the two systems when allocating party seats for filled first preference quotas.
• There is a difference on allocating final seats based on partial quotas or remainders. List-PR quota systems allocate seats on highest remainder, while PR-STV uses preferences which can vary the result from highest remainder.

(One caveat here. Under PR-STV you get rare cases where candidate choice changes the order of party candidate election. Labor’s Lisa Singh defeated a candidate above her on the Labor ticket in Tasmania at the 2016 double dissolution election without changing the number of Labor members elected. Experience with Hare-Clark makes Tasmanian voters more likely to vote for candidates BTL. Significantly Singh’s victory was at the first election after the abolition of GVTs.)

Comparing a PR-STV result to what would have occurred using List PR tells you how preferences changed the result. And as I show below, when GVTs were used for Senate elections, the number of highest remainder leads overturned was very significant. Arranged preferences deals through GVTs meant parties with a large partial quota could be overtaken by parties with a fraction of the leading party’s vote. (See Ricky Muir example mentioned earlier.)

With the abolition of GVTs, parties with a large residual quota are under less threat of defeat due to the weakening of preference flows.

In short, when you abolish GVTs, the system starts to behave like List PR with a highest remainder method of allocating the final seats. Preferences become less important and parties with a higher partial quota are rewarded.

And to clarify in case I slip-up and refer to a party with a higher vote being advantaged, what I am referring to is parties with a higher partial-quota or remainder. Under List-PR, only the parties with the highest partial quotas can win seats. Under PR-STV, preferences can allow a lower placed party to win a seat.

Parties with a vote high enough to fill multiple quotas are brought back to the playing field by filled quotas being removed and only the party’s remaining votes, its residual or partial quota, competing for final seats with the partial quota of parties that polled less than a quota. It is at this stage of competing partial quotas that preferences play a part. The abolition of GVTs advantages parties with a higher partial quota where GVTs could be engineered to elect a lower polling parties.

Classifying Victories

To compare Senate PR-STV results with the highest remainder List-PR method, I use the following four measures.

• Filled quotas – seats allocated to groups on quotas filled by first preference.
• Highest remainder – seats won by parties that began the distribution of preferences with the highest remainder or partial quota.
• Trailing wins – candidates elected from a trailing partial quota. These are parties elected on preferences, passing a candidate with a higher remainder.
• Parties passed – the number of parties with a higher remainder passed by trailing winners.

The table below applies these measures to half-Senate elections for six Senators per state since 1990. The totals under “Filled Quotas” and “Highest Remainder Wins” are the number of members elected under the Senate’s electoral system that would also have won under a List-PR/Highest Remainder system. The numbers under “Trailing Wins” shows where preferences changed the winner, and “Parties Passed” the number of higher polling parties that did not win.

The last four lines are the most dramatic. The use of “preference harvesting”, where all small parties used GVTs to swap and control preferences ahead of larger parties, led to nine trailing wins in 2013. Results since the abolition of GVTs, shown by the final three lines in the table, show an increase in the number of highest remainder wins and a near disappearance of trailing wins. Abolishing GVTs increases the importance of first preferences and diminishes the power of preference transfers.

Table 1: Half-Senate Result Analysis – 1990-2025

Election	Filled Quotas	Highest Remainder Wins	Trailing Wins	Parties Passed
1990	28	6	2	2
1993	30	4	2	3
1996	28	7	1	1
1998	24	7	5	5
2001	25	6	5	6
2004	29	6	1	3
2007	27	8	1	2
2010	27	7	2	4
2013	21	6	9	33
2019	22	14	..	..
2022	23	13	..	..
2025	22	12	2	2

Source: Based on Table 8.1, p.193, Antony Green, “The Senate Results” in Anika Gauja, Peter Chen, Jennifer Curtin and Juliet Pietsch (eds), “Double Disillusion: The 2016 Australian Federal Election”, ANU Press, Canberra 2018. Original table covered 1977-2016. Above table covers six-vacancy half-Senate elections since 1990, updated for the last three elections but excluding the 2016 lower quota double dissolution election.

The number of Senators elected from filled quotas has declined over three decades in line with slipping support for Labor and the Coalition. Where once both major groupings could poll above 35% and have a chance to fill three Senate positions, more recent elections have seen support for Labor and the Coalition dip to the low 30s and high 20s. For example, the 2025 election was the first since the parliament was expanded in 1984 at which the Coalition was reduced to electing only two Senators from each state.

And as I summarised in the paragraph before the table, GVTs saw an increase in parties winning from behind on preferences and peaking at nine in 2013. At the three half-Senate elections since the abolition of GVTs, the number of highest remainder wins has reached double digits, and the number of Senators winning from trailing positions shrunk.

Which proves the point I keep making. The abolition of GVTs advantages parties with larger partial quotas, that is higher remainders at the start of the count, and disadvantages parties that have greater reliance of preference transfers.

The Party Dimension of Leading and Trailing Wins

At the 12 half-Senate elections held since 1990, Labor has never won a seat where its partial quota trailed. Over 12 election, Labor has never come from behind to win on preferences. On 11 occasions Labor has lost seats where it began the count with the highest remainder.

This oddity has complex causes related to electing six Senators meaning Labor was always strongly positioned to win two seats but competed with other parties for a third. Until 2001 this often saw third party and Coalition preferences elect Australian Democrat Senators, and since 2004 Labor’s third spot has been a contest against the Greens. This quirk of electing an even number of Senators is not relevant to five-member Victorian Legislative Council regions, as I’ll explain in my next post which will replicate my Senate analysis for the Legislative Council.

The Coalition parties have done better, winning six seats after starting with the highest remainder, and only losing three after starting with the highest remainder. The Coalition lost two leading seats to micro-parties at the 2013 election which played a part in the Coalition leading the move to abolish GVTs. That move was initially backed by Labor but support was withdrawn in early 2016. The abolition of GVTs was eventually passed with the support of the Coalition, Greens and Nick Xenophon.

Between 1990 and 2001, the Australian Democrats won two Senate positions with filled quotas, 10 after starting with the highest remainder and eight from trailing positions. This includes three seats in 1998 that would have been won by One Nation were it not for Labor and the Coalition actively preferencing against One Nation. The Democrats also lost three seats after recording the highest remainder, two of those being passed by the Greens on Labor preferences as part of preference deals. Democrats were a beneficiary of preferences as both major parties acted to elect a Democrat if they could not elect a third Senator.

The Greens have received the most benefit from the abolition of GVTs. With GVTs in use, the Greens won eight seats from leading positions and four from trailing positions between 2004 and 2013. At the three elections since GVTs were abolished, the Greens have won 16 seats from leading quotas and another two from filled quotas. The Greens have consistently had a strong enough first preference vote to win Senate seats, and the abolition of GVTs has ensured the party is no longer under threat from being defeated by complex GVT preference deals.

One Nation lost two seats each from leading positions in 1998 and 2001 after being locked out of GVT deals. Since the abolition of GVTs, One Nation has had a strong enough vote to win three times from leading positions in Queensland. For the first time One Nation won half-Senate seats outside of Queensland in 2025. In both NSW and WA, One Nation came from behind to win election on voter controlled preferences.

(On an amusing side note, the Greens’ Kerry Nettle was not elected to a NSW Senate seat in 2001 through a “deal” with One Nation. Of the many parties that put One Nation last in 2001, the Greens were the only one to contact One Nation and inform them of their decision. As a reward for this polite gesture, One Nation listed the Greens in a favourable position on its GVT and to its surprise helped elect Nettle.)

The above paragraphs back my already stated conclusions that the abolition of GVTs advantages parties that start the count with a significant votes. It reduces the chances of lower polling candidates catching parties with higher partial quotas.

And the abolition of GVTs ends preference deals designed to block certain parties electing Senators, as occurred with the Nuclear Disarmament Party in 1984 and One Nation in 1998 and 2001.

GVTs used to deliver 90-95% preference flows to other parties. Abolishing them produces much weaker preference flows as many voters mark their own preference sequence. Or choose not to indicate preferences at all, the exhausted preferences from voters not choosing being another advantage for leading parties.

Only parties that can distribute many how-to-votes can influence how their voters mark preferences. Parties that don’t campaign have essentially random preferences, a long way from GVT days when even the smallest party could deliver flows above 90%.

And another observation. The reason some parties attract lots of first preference votes is because they are better known than smaller parties. With GVTs abolished and voters now completing their own preferences, these better known parties with higher votes also tend to attract more preferences.

It is why the abolition of GVTs has aided Labor, the Coalition, Greens and One Nation. Voter awareness of these parties delivers them both higher first preference votes and higher flows of preferences.

Winning From Partial Quotas

The starkest difference between the operation of GVTs, and what has happened since their abolition, is revealed when you look at the initial partial quota of elected and non-elected parties.

The first table below shows the number of candidates elected from partial quotas. The second shows the partial quotas of candidates who were defeated. Results are grouped on 0.1 quota bands, with the upper bound % vote shown in brackets.

The first table of shows all candidate elected from partial quotas. Where the elected candidate was a trailing candidate, the number is coloured red. The influence of GVTs at the 2013 election is stark.

Table 2: Half-Senate Elections 2013-2025 – Election from Partial Quotas

Initial Partial Quota	2013 (GVTs)	2019 (No GVTs)	2022 (No GVTs)	2025 (No GVTs)
0.9 < 1.0 (14.3%)	2	1	2	2
0.8 < 0.9 (12.9%)	2	3	4	3
0.7 < 0.8 (11.4%)	2	4	1	2
0.6 < 0.7 (10.0%)	2/1	5	1	2
0.5 < 0.6 (8.6%)	..	1	2	1
0.4 < 0.5 (7.1%)	2	..	1	2/2
0.3 < 0.4 (5.7%)	1	..	1	…
0.2 < 0.3 (4.3%)	1	..	1	…
0.1 < 0.2 (2.9%)	..	..	..	…
< 0.1 (1.5%)	2	..	..	…

Based on Table 10.15, p220, in Antony Green, “The Senate Results”, chapter 10 of Anika Gauja, Marian Sawer and Marian Simms (eds), “Morrisons’s Miracle: The 2019 Australian Federal Election”. Data based on original WA Senate election, not 2014 re-run. Numbers in red indicate parties that came from behind to defeated candidates with higher partial quotas.

In 2013 there were only six leading candidates elected, all from above 0.6 partial quotas. There were nine trailing candidates elected, including six from under 0.5 quotas. It’s worth highlighting which parties were elected and which were defeated along with their initial quotas.

• NSW – on a giant ballot paper with small fonts, the Liberal/National group lost votes through confusion with the Liberal Democrats in the prominent first column on the ballot paper. The Liberals elected as third Senator from 0.39 quotas, passing the Greens on 0.55 quotas.
• VIC – The Coalition on 0.81 quotas and Labor on 0.27 lost out to lower polling parties. Labor’s preferences surplus elected the Greens who trailed the Coalition but started on 0.76 quotas. This was a victory that could have been achieved without GVTs. The Australian Motoring Enthusiasts Party passing the Coalition from just 0.035 quotas was entirely due to GVTs.
• QLD – no trailing wins.
• WA – Labor failed to win from 0.86 quotas, the Australian Sports Party was elected from a trailing 0.016 quotas. The Liberals on a trailing 0.74 quotas were elected by Nationals on 0.35 quotas, a victory almost certainly possible without GVTs. The Greens on a trailing 0.66 quotas were elected. Palmer United Party also missed out from 0.35 quotas. A few dozen votes in a different direction would have elected Labor and Palmer United in place the Greens and Sports Party. This narrow margin came into play when it was discovered that around 1,200 ballot papers had been lost. The result was overturned and a second election held in April 2014.
• SA – A gang-up to prevent the Nick Xenophon Team winning a second seat saw the team miss out despite 0.74 quotas towards a second seat. Labor also missed out on a second seats despite a 0.59 partial quota. The final seats went to the lower placed Greens on 0.50 and Family First 0.26 quotas. The use of GVTs picking and choosing candidates within party tickets totally distorted the result.
• TAS – The Liberal Party on 0.63 quotas to a third seat were defeated by lead Palmer United Party candidate Jacqui Lambie on 0.46 quotas. This result could have occurred without GVTs as it is similar to One Nation’s victory in NSW in 2025.

The 2025 election saw the first cases of post-GVT trailing party victories. In NSW, One Nation on 0.42 quotas attracted enough preferences to narrowly pass Labor who began the count on 0.63 quotas. In WA, One Nation from 0.41 quotas passed Labor on 0.53 quotas to win the final seat.

The other three victories from under 0.5 quotas post-GVTs were highest remainders wins that did not need preferences and occurred in 2022. United Australia Party won in Victoria from 0.28 quotas as previously mentioned, Labor winning a third seat from 0.42 quotas in WA, and the SA Liberal Party a third seat from 0.39 quotas.

There have been three cases where a partial quota above 0.5 didn’t elect a Senator post-GVTs. Two were in 2025, NSW Labor on 0.63 and WA Labor on 0.53 mentioned in a previous paragraph about One Nation winning on preferences. The third was QLD Labor in 2019 from 0.58 quotas, missing out as the lowest partial quota in a four-way race for three seats.

My final comments relates to the Table 3 below that classifies the partial quotas of defeated parties. It shows big numbers for parties that poll less than 0.1 quotas on large Senate ballot papers.

Other than that bottom row, Table 3 is essentially the reverse of Table 2. There were six parties previously mentioned in 2013 that were defeated despite polling above 0.5 partial quotas, including three above 0.7 quotas. Only three parties have missed out from above 0.5 quotas since, and every party above 0.7 has won a seat.

Which again shows the distorting impact of GVTs. In 2013 parties with high partial quotas could be defeated by arranged preference tickets. That has ended with the abolition of GVTs. All parties with a partial quota above 0.5 are now well positioned to win, above 0.4 can win on preferences. And even split of partial quotas can produce almost accidental victories like Ralph Babet at the 2022 Victorian Senate election.

Table 2: Half-Senate Elections 2013-2025 – Parties Defeated from Partial Quotas

Initial Partial Quota	2013 (GVTs)	2019 (No GVTs)	2022 (No GVTs)	2025 (No GVTs)
0.9 < 1.0 (14.3%)	..	..	..	..
0.8 < 0.9 (12.9%)	2	..	..	..
0.7 < 0.8 (11.4%)	1	..	..	..
0.6 < 0.7 (10.0%)	1	..	..	1
0.5 < 0.6 (8.6%)	2	1	..	1
0.4 < 0.5 (7.1%)	1	1	1	1
0.3 < 0.4 (5.7%)	2	2	1	4
0.2 < 0.3 (4.3%)	7/1	4	17	9
0.1 < 0.2 (2.9%)	9	27	20	20
< 0.1 (1.5%)	159	100	86	59

Based on Table 10.15, p220, in Antony Green, “The Senate Results”, chapter 10 of Anika Gauja, Marian Sawer and Marian Simms (eds), “Morrisons’s Miracle: The 2019 Australian Federal Election”. Data based on original WA Senate election, not 2014 re-run. Numbers in red indicate parties that were passed and defeated by candidates with lower partial quotas.