Less marginal seats: the new shape of the electoral battleground


Last Saturday’s election was not a landslide: far from it. While it appears the Liberal/National coalition has gained a small swing nationally, there are lots of areas which swung in the opposite direction.

So I was interested in zooming out to get a sense of how many seats had swung in each direction, and how they fit into the respective “marginal”, “reasonably safe” and “safe” categories.

I’ve defined these categories as follows:

  • Marginal – 0-6% margin
  • Reasonably safe – 6-12% margin
  • Safe – 12%+ margin

Overall I have found a reduction in the number of marginal and reasonably safe seats and an increase in the number of safe seats, mostly on the Coalition side, but also that both major parties have seen seats moving in both directions.

I should note that I have included Cowan and Lilley as Labor seats, and Bass, Chisholm and Macquarie as Coalition seats post-election. I have also treated Wentworth as a safe Coalition seat and Chisholm as a marginal Coalition seat before the election.

This first table shows the number of seats in each category before and after the election.

Coalition marginal2522-3
Coalition reasonably safe2926-3
Coalition safe21309
Crossbench marginal220
Crossbench reasonably safe110
Crossbench safe231
Labor marginal2421-3
Labor reasonably safe26260
Labor safe21201

You can firstly see a net increase in Coalition seats of three, and a drop of two Labor seats, and a gain of one for the crossbench. That reflects the latest expected numbers of 78-67-6.

The total number of seats considered “marginal” has dropped from 49 to 43, with both parties holding less marginal seats than they did before the election.

Labor previously needed a uniform swing of 1% to win the 76 seats necessary for a bare majority (an increase of 5). They now need nine seats (assuming no change in who is leading), which requires a uniform swing of 3.4% on the latest figures.

The Coalition previously needed a swing of 0.02% to regain their majority. A swing of 0.8% would now see them lose their majority.

Next up, this chart shows the seats by their pre-election category and how many seats in that category saw a swing to the incumbent or away from the incumbent.

CategorySwing to incumbentSwing away from incumbent
Coalition marginal178
Coalition reasonably safe209
Coalition safe1011
Crossbench marginal11
Crossbench reasonably safe1
Crossbench safe2
Labor marginal1212
Labor reasonably safe917
Labor safe912

There is no broader trends of seats in certain marginality categories swinging one way or the other. In fact it appears that both major parties gained support in at least half of their marginal seats, with the Coalition doing particularly well.

The Coalition also gained swings towards them in their safer seats, while the opposite was true for Labor, which will tend to help the Coalition national two-party-preferred figure without having an impact on the seat count. Yet in every category at least one third of seats are bucking the trend.

Finally I decided to check how many seats are now in a different category to what they were before the election.

63 seats out of 151 have changed category. This includes 28 marginal seats. In eight of these seats (6 Labor and 2 Coalition) the seat changed hands. In the other twenty the seat became safer for the incumbent party.

12 reasonably safe Coalition seats moved up a category, while it was more common for Labor seats to move down the category.

While there has been some general shift towards the Coalition, and a reduction in the breadth of the marginal seat battleground, it is more interesting to see where these most marginal seats are.

Prior to this election, the ten most marginal Coalition seats on the pendulum included five Queensland seats, as well as three in New South Wales, one in Victoria and one in South Australia.

Now there is only one Queensland seat on this list (Longman), as well as three seats in New South Wales (Macquarie, Reid and Wentworth), two in Victoria (Chisholm and Higgins), two in Tasmania (Bass and Braddon) and one each in South Australia (Boothby) and Western Australia (Swan). That makes for quite a different election next time around.

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  1. Thanks as ever for sharing your brain with all of us Ben. It’s so good and so useful. (Psst – near the end, ‘Macquarie, Red and Wentworth’ – should that say something other than Red?)

  2. NSW is far more likely to be the main battleground next time. Robertson, Page, Lindsay, Banks and Reid (and Macquarie if Labor end up losing it) – that’s half of Labor’s pathway to majority right there. There will be a state coalition government entering its 11th year as well and depending on its performance voters might be starting to get weary.

    A lot of the QLD seats outside of the south-East will be simply out of reach for Labor in 2022 unless something spectacular happens.

  3. The fact that Higgins is now the Coalition’s second most marginal seat in Victoria says a lot about the shifting dynamics between their fortunes in traditional wealthy seats and middle class suburban seats that has been discussed a lot lately. Who would have thought the Libs could ever be safer in the seat containing Pakenham & Narre Warren than they are in the seat centered on Toorak & Malvern?

  4. Ben: awesome analysis. Thank you. Next federal election will be interesting. I wonder: QLD swings wildly, and based on history, if Morrison doesn’t deliver as promised, they’ll swing back…

  5. Ben

    My memory of the 2010, 2013 and 2016 elections were of a tendency for quite significant swings at the first two toward the coalition, in 2010 in safe seats (on both sides), but not marginals; then in the marginals, and then in ’16, much of the swing to Labor being again in safe seats. Is there a underlying trend in all of these calcs, or merely a spread of swings in seats that simply aren’t closely fought as unlikley to change sides?

  6. @ Trent

    I am told also a measure of demographic change though: the houses on half acre blocks in leafy streets being replaced (to an extent) by urban infill and aparatments. That’s a dynamic we’ve seen before – it is part of the story of how the old seat of Lowe in Sydney went from a comfortable coaltion seat to a marginal to a safeish labor one, and now, in the guise of Reid (which is much more like the old Lowe than the old Reid) a more or less comfortable coalition seat.

  7. True, but that doesn’t happen very often Mick. Labor losing by such big margins makes it so much harder for them to win next time. More time to sandbag, entrench, for demographics to change an so on.

    Will Labor even bother to campaign in Capricornia, Dawson, Herbert etc when there are other more low-hanging fruit? Doubtful, unless a big swing is on in QLD a la 2007.

  8. A good example of a big swing to Labor is the seat of Kingston in southern Adelaide – while in the past it was always marginal and every MP has been defeated, I wouldn’t be surprised if Amanda Rishworth retires on her own accord and hands it over to another Labor MP.

  9. MQ

    There are some seats that swing because of demographic changes. The southern sydney seat of banks for example had a member Leo mcLeay who was convicted of travel Rort but got a swing to him 20 years ago. The seat have over the last 20 years moved from safe ALP to safe Liberal a move of over 20%

  10. Leo McLeay. Was the MP for Watson most recently… was never a marginal seat Daryl Melham was the last alp MP for Banks ….yes when he won the seat was safe alp and all the Revesby suburbs were approx 60% alp also some of Punchbowl was in the seat which voted 70% alp also Oatley. And Blakehust. Connell’s point were moved into the seat….the combination of the gentrification of Revesby the Removal of Punchbowl and the addition of conservative areas made the seat marginal

  11. Pyrmonter that’s definitely true in South Yarra where a lot of high rise has gone up, and the suburb has gone from reliably Liberal leaning (~55% two party) to reliably Greens leaning (~55% two party) over the past few elections, state and federal. It has a big population too. For this reason I see the state seat of Prahran staying relatively safe Greens on current boundaries.

    Most suburbs in the heartland of Higgins are relatively untouched by much development though and still fit the leafy, old money profile pretty accurately.

  12. That is what we like to see, lots of marginal electorates which should make the incumbent MHR actually work or work harder, an excerption to work was the now retired Michael Danby who never worked much for constituents in Melbourne Ports (now Macnamara) for 20 years.

  13. Pyrmonter

    Demographic change is overrated, Higgins current boundaries brings it in tough with a number of difference demographics that previously were in difference electorates.

    The Prahran/South Yarra has for a long time been home to a younger population drawn to the Chapel St scene and large, then there is Toorak/Malvern which is traditionally been Higgins remains home to large family homes, from there the seat branches north/east and south/east into two less wealthy middle income areas. The only recent change in the South Yarra area has been the large high rises on the north side of Toorak Rd.

    The Prahran area has always been more progressive than Toorak/Malvern with the ALP enjoying some support around Murrumbeena and Ashburton at the Eastern end of the electorate.

  14. Pencil that’s probably the most accurate profile of Higgins I’ve read.

    I think looking at who holds the overlapping state seats reflects those differences too – West end is held by the Greens (Prahran), middle is held by the Liberals (Malvern) and South East corner is held by Labor (Oakleigh) at state level. It’s a more complex and diverse seat than the common categorisation of “blue ribbon” usually implies.

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