ACT election data suggests neither Liberal nor Greens voters would want a coalition between the parties

After weeks of talks, the somewhat outlandish idea that the Canberra Liberals and ACT Greens could form a governing coalition to seize power from Chief Minister Andrew Barr was ruled out for being, well, a bit too outlandish.

One of the suggestions for a power-sharing arrangement could have seen both Greens leader Shane Rattenbury and Liberal leader Mark Parton taking turns serving as chief minister.

After weeks of conversations, Mr Rattenbury determined the idea had  "no support" within his party, while elected Liberals reportedly objected to the idea of allowing a Green to serve as chief minister. 

But what about the voters from the 2024 ACT election who put them there in the first place?  What would they think of a Liberal-Greens coalition? 

Preference data from the last election suggests Greens and Liberal voters might have had a lot to say about it. 

Greens voters don't like the Liberals much 

The ACT uses the multi-member Hare-Clark electoral system, with five electorates each electing five members. That means that we don't see a traditional two-party preferred count as we see in federal elections.

But helpfully, the ACT electoral commission does publish the details of every single ballot paper, meaning we can see where everyone's votes went after their first preference. 

It turns out that ACT Greens voters behave in much the same way as Greens voters nationally: they don't much like the Liberal Party.

While voters are never explicitly asked which party they'd prefer to form government, we can calculate a version of a two-party preferred count by counting up the number of voters who ranked a Liberal candidate before any Labor candidates, or vice versa, or neither.

Territory-wide, across all ballots, that count shows a clear majority of Canberrans ranked a Labor candidate above any Liberal candidate in the 2024 election.

It also demonstrates that Greens voters overwhelmingly prefer Labor to the Liberal Party.

Territory-wide, 68.7 per cent of Greens voters preferenced Labor ahead of the Liberals in 2024, compared to just 8.9 per cent who preferenced the Liberals ahead of Labor. 

The final 22.5 per cent of Greens votes didn't have any preference recorded for either of the two parties.

Those preference flows are broadly similar across all five ACT electorates.

In fact, most Greens voters sent their vote straight to Labor without passing through any other parties or groups, without passing go, and without collecting $200.

Most of the rest preferenced either Independents for Canberra or the Animal Justice Party once they left the Greens ticket.

How might they have reacted (and voted in 2028) had a Rattenbury-Parton government gone ahead?

The two-party contest, territory-wide

In 2024, Labor earned 34.1 per cent of the first preference vote across the ACT.

The government ended up only a couple of thousand votes ahead of the Canberra Liberals, with 33.5 per cent.

But Labor picked up the bulk of preferences.

Greens votes flowed more strongly to the Labor party than any of the other minor parties and groups.

Across the entire territory, we find that 50.8 per cent of voters ranked a Labor candidate above any Liberal candidate, 40.8 per cent of voters ranked a Liberal candidate above any Labor candidate, and 8.4 per cent of voters did not vote for a candidate from either party.

Although this notional two-party preferred count has no bearing on the numbers in the ACT Legislative Assembly and the formation of government, you can see how Labor would react if they were turfed out of office.

What about Liberal preferences?

The picture is a little murkier here because most Liberal voters never express a preference between the Greens and Labor, with their votes exhausting the moment they run out of Liberal candidates.

Of those that do express a preference, they generally opt for Labor over the Greens.

The detailed data shows a far more even spread of Liberal preferences across the parties and groups.

But again, how would Liberal voters react if their favourite party made Shane Rattenbury the chief minister?

It's tricky to see how a Liberal-Green coalition government would function in practice in the ACT.

It's tricky to work out how both parties would've been able to sell the arrangement to their voters.

Perhaps that's why the proposal is dead in the water.