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Who would benefit from an expanded parliament?

September 29, 2025 - 09:30 -- Admin

Today’s blog post is inspired by a strange opinion piece in the Nine papers yesterday by former federal Liberal Attorney-General George Brandis.

Brandis’ piece (in addition to incorrectly stating that the last increase in the size of parliament was in 1987) makes two main claims about political advantages for Labor and the Greens in the expansion of parliament:

  • “Because most population growth is in city electorates,” an expansion of the House of Representatives “would be a significant advantage to Labor”, and;
  • that “the Greens would be the big winners from an increase in the size of the Senate.”

Neither of these claims is remotely true. Any increase in the urban share of seats in parliament will happen whether or not the parliament is increased, and the Greens are uniquely placed to not benefit from an expansion in parliament – at least until each state elects at least nine senators.

First, let’s tackle the claim for the House of Representatives. It is true that, over time, we have seen an increasing proportion of seats in urban areas and thus a smaller share in rural areas. As long as there has not been a substantial number of seats in total, this has required rural seats to take in larger areas.

But an expansion of parliament wouldn’t just give new seats to those fast-growing areas – they would go everywhere.

If the Parliament was expanded to about 200 seats (which would involve each state electing 16 senators), then New South Wales would gain 16 extra seats on top of their existing 46. Three existing seats would get turned into four. This applies all over the state. For example, the seats of Richmond, Page and Cowper would be redrawn to be four seats. The vast western seats of Farrer, Riverina and Parkes could also be redrawn to create one extra seat. Yes, nine of the new seats would be added in the Sydney region currently covered by 26 seats, but the relative proportions would be the same.

I see no reason why this should provide any partisan benefit. If anything, it may harm the existing government since they would hold many notional seats without incumbent MPs to defend them (although the large scale of their 2025 victory might reduce this problem).

As for the Senate, it is even easier to disprove.

Andrew Conway has provided a helpful website which allows users to recount Senate results dating back to 2013, using real Senate ballot data. For our purposes today, it’s most useful as a way to re-run election results with a change in the number of senators elected.

I have performed this analysis back to 2016 – the first election using the current Senate electoral system. For 2016, I have used the special count which elected six senators per state – a legislated requirement at double dissolutions to provide information to the Senate as to who should receive a longer Senate term.

I have then compared those 6-senator results to the outcomes if seven, eight or nine senators were elected. Bear in mind that a nine-senator election would be an enormous increase to the size of parliament, and Brandis is mostly addressing seven- or eight-senator expansions.

I have then calculated the changes at a national level at each election. Territory senators are not included – that’s a separate conversation.

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In his op-ed, Brandis said that

Reducing the quota by increasing the size of the Senate would virtually guarantee the Greens one seat in each state at every half-Senate election, give them a realistic chance – after preferences – of a second seat in their stronger states and make it probable they would win three per state at a double dissolution.

(He also mentions that the Greens would have eleven seats without the defection of Lidia Thorpe but doesn’t mention the defection of Dorinda Cox – it’s not a well-researched article.)

Benefits of a larger parliament are shared around, but the Greens are actually in a uniquely poor position in this regard.

The majority of new seats go to the major parties, with One Nation also doing relatively well.

The Greens comfortably win all of their Senate seats now, but are a long way away from winning a second seat in any state. An expanded parliament would have increased their numbers in 2016, but at the last three elections the Greens wouldn’t have gained a single seat. They would only start winning extra seats if the parliament expanded to nine senators per state – but at that point, they would be winning 1-2 out of 18 new senators. Their gains are dwarfed by Labor and the Coalition, and even by One Nation.

The main beneficiaries are either the major parties, who win enough votes to win multiple seats, or parties that fall short of winning a single seat under the status quo. This is primarily One Nation, but also Legalise Cannabis would have won one of eight seats in Queensland in 2022.

How would these changes shift the overall balance of the Senate? They wouldn’t do much. Usually the left-right split of these seats is close to even.

The benefits of an expanded parliament may be predominantly on the side of one party or another in a particular election, but over time they won’t have a particular bias one way or the other. But a more diverse and representative parliament that is closer to the people would benefit us all.