Federal redistributions for Victoria, South Australia and the Australian Capital Territory have been finalised over the past fortnight, a development that removes procedural obstacles for the staging of a normal election for the House of Representatives and half the Senate. At the bottom of this post is a new electoral pendulum based on post-redistribution margins. This illustrates that the goverment has, notionally speaking, lost its majority, being reduced from 76 seats to 74 in a chamber that increases in size from 150 to 151. The Liberal-held Victorian seats of Corangamite and Dunkley move into the Labor column (just barely in the former case – others who calculate the margins might very easily fall the other way), while Labor also gains new seats in Victoria and the Australian Capital Territory, but loses a seat through the abolition of Port Adelaide in South Australia. That gives Labor 72 seats, assuming the cross-bench remains unchanged with its existing five members. All margins shown in the pendulum are Labor-versus-Coalition, except in the five seats held by minor parties and independents.
The main changes made from the draft to the finalised boundaries are cosmetic, in that Corangamite will retain that name and not be renamed Cox, and Batman will be renamed Cooper. Beyond that, minor changes were made to eleven seats in Victoria. The most significant change was to Deakin, costing it around a third of the 19,000 voters it was originally to gain from Casey in the east, and compensating it at the other end with more than 3000 extra voters in Vermont South from Chisholm. The electoral impacts are very slightly advantageous to the Liberals, boosting their margin in Dunkley relative to the draft proposal by 0.4% to 6.6%. There are no changes to the draft as far as I can see in South Australia, and only a minor and inconsequential one in the Australian Capital Territory.
The links below provide my full accounting of the new margins, both for the three redistributions just finalised, and the other three concluded since the last election.
The two-party results featured above are strictly Labor-versus-Coalition, which leaves some explaining required where this doesn’t apply. None of the three Melbourne inner-city seats where the Greens threaten Labor has been significantly changed. There is no difficulty counting a new Labor-versus-Greens result in Wills and the seat now known as Cooper, since neither gains territory from a seat in which no Labor-versus-Greens count was conducted. David Feeney held the Greens off in Batman by 1.0% in 2016, but I now make it at 0.5%, while Ben Raue at The Tally Room has it at 0.7%. However, given Ged Kearney’s succession to the seat in the March by-election, comparisons based on the 2016 election are rather academic. Labor’s margin over the Greens in Wills is unchanged at 4.9%. Cathy McGowan’s seat undergoes only minor changes, although territory gained from Murray (now Nicholls) now provides about 4% of its voters, which obviously cannot be used to measure support there for McGowan. This is not enough to significantly alter the position of McGowan, who held off Sophie Mirrabella in 2016 by 4.8%.
In South Australia, the Nick Xenophon Team reached the final count in four seats, winning Mayo from the Liberals by a margin of 5.0%, and finishing 2.0% and 4.7% short of Liberal incumbents in Grey and Barker, and 14.9% short of Labor in Port Adelaide. In no case can new margins be determined: Port Adelaide is abolished; Grey and Barker have both gained territory from Wakefield, respectively accounting for around 15% and 8.5% of their voters, where no Liberal-versus-NXT count was conducted; and Mayo gains territory from Kingston and Boothby, collectively accounting for over 17% of the voters, neither of which had useable counts.
Pendulum over the fold below. Seats whose notional party has changed are indicated with an asterisk. The “redist.” column records the effect on the margin of redistributions, where they have been conducted (i.e. everywhere but New South Wales and Western Australia). Margins shown for the five seats held by minor parties and independents are their winning margins at the 2016 election, with no change made for the redistribution.