Just one more week until election day in Australia and it appears clear that Tony Abbott and the Coalition will be winning government and it probably won't be particularly close. In the interests of not burying the results the model currently predicts the Coalition a 100% chance of winning government with a median seat result of 87-60 (3 independents). Coincidentally half of the Senate is also up for election and the Coalition will be hoping to, if not win control in their own right, at least help ensure the election of sufficient Senators that are at least somewhat friendly to their overall objectives.
The method of electing Senators is ridiculously complicated. There isn't, in my opinion, any way to realistically model likely outcomes. The subjectiveness of inputs, given there is no polling, combined with the byzantine nature of party assigned preferences, makes anything more than vague predictions unrealistic. So I'm going to suggest a potential range of outcomes in each state without assigning exact probabilities.
Each state is represented by 12 Senators. Every three years six of these Senate positions are up for election. All six Senators are elected out of the same pool of votes. Any parties or candidates receiving more than 14.3% of the total formal votes cast is elected to one of the available seats. In the event that all six vacancies are not filled at this point then we get into preferences (like the house, but way more complicated).
Preference allocation occurs in rounds. First the party with the lowest vote total is eliminated from contention. Then the votes gathered by this party are allocated to another party according to a list lodged by all parties with the Australian Electoral Commission a few weeks ago (or according to the voters wishes, if they are prepared to fill out as many as 110 boxes (NSW) in sequential order, not many people do that). If this process means a party has cleared the 14.3% threshold they are elected. If not then another round of preference allocation occurs.
There are a lot of parties running for Senate. It varies by state but often dozens run, most parties get almost no votes but due to the preference allocation system works it is quite possible to be elected to a Senate seat on way less than 14.3% of the primary vote. In New South Wales this year senate papers are printed in 7 point font and voters are provided with magnifying glasses so they can read them. It's not the best system.
The territories also elect two Senators each (at the same time as the House, don't wonder why) giving a total of 76 Senators. 39 Senators, one more than half, are required to pass legislation.
Currently the Left-leaning parties control the Senate (Labor, 31 seats; Greens, 9 seats). The Coalition have 34 Seats and there are two other Senators. The independent Nick Xenophon in South Australia and John Madigan of the DLP in Victoria. The Coalition would like to get as close to 39 seats as they can, but at the very least they would prefer Labor and the Greens are reduced to 37 seats or less so that they are unable to block legislation.
I'll talk about each State's Senate possibilities in each State's own section.
As previously the model assumes that the Independent Andrew Wilkie in Denison, Adam Bandt of the Greens in Melbourne, and Bob Katter of an Australian Party of the same ilk in Kennedy will all win reelection. This is not an entirely safe assumption.
The next few paragraphs are basic Australian background and housekeeping related information. If you've read my previous Australian Election modelling diaries you might like to skip straight to the state breakdowns where you'll find the usual tables now include percentage chances for the Coalition to win each seat.
Currently Australia is governed by the Labor party (centre-left, loves unions) with the support of a number of independents (3 conservative, 1 Laborish, 1 idiosyncratic but left-leaning) and the Greens (progressives). The opposition is known as the Coalition, with an uppercase C as their coalition is permanent, and is composed of the Liberals (centre-right, hates unions, loves free markets) and Nationals (conservative agrarian socialists, loves protectionism). The Labor party need the independent and Green support as they do not have enough seats to govern in their own right (and in fact have less seats (71) than the Coalition (72)).
Voting in Australia is compulsory and uses a preferential ballot (this means that in certain seats the way parties direct their supporters to allocate their preferences will be crucial) in single-member seats for the House of Representatives.
Finally before we get to the numbers I'll just mention a few details in regards to the model I am using. The model takes into consideration the prior voting history of the electorate, incumbent strength (where applicable), and public polling. It doesn't account for potential asymmetric swings within states (not enough polling data available). I'm interested to see how much that ends up mattering.
Tables in this diary are colour coded. Shades of red reflect Labor held seats and predictions, shades of blue represent Liberal held seats and predictions (the occasionally different party names and abbreviations are courtesy of local party branches having inconsistent names), independents are grey, Greens are light green (shocker), and Nationals are dark green.
New South Wales
Things are deteriorating badly for Labor in New South Wales. There is evidence that swings against Labor in Western Sydney are going to be stronger then elsewhere in the state. The model isn't accounting for that (assuming it is true) and I wouldn't be surprised if Labor lose more seats in Western Sydney than is predicted.
In 2007 New South Wales elected three Coalition and three Labor Senators. Labor won't elect three senators again. The third Labor seat could be won by the Greens, or Family First, or the Shooters and Fishers, or even the legendary Pauline Hanson.
Victoria
The Liberal member for the seat of Indi (they are rather personally unpopular) is receiving a strong challenge from an independent. I've changed the rating of Indi to Likely Lib, though this is to reflect the chance of the independent winning not any chance for Labor.
In 2007 Victoria elected three Senators from both the Coalition and Labor. Labor will not poll well enough to repeat the feat and will almost certainly lose a seat to the Greens. The Coalition may struggle to hold their third seat against a flood of minor parties (they failed to win a third seat in 2010, losing out to the DLP (socially conservative, economically left-wing)).
Queensland
Labor are struggling in Queensland. Like everywhere. Seat based polling has even Prime Minister Rudd behind in Griffith.
Labor have negotiated Katter's Australian Party (KAP) preferences across northern Queensland. This will presumably give Labor a better chance in these seats (Leichhardt, Herbert, Capricornia, Flynn, Dawson) than the model predicts. I've got neither past election data, or polling, to help me model this.
In 2007 Queensland boringly elected three LNP Senators and three Labor Senators. That won't be repeated. Labor have chosen to preference KAP ahead of the Greens in Queensland. They might not have many votes to give out though. Even so the most likely outcome will be three LNP, two Labor, one KAP. It remains possible the Greens could win a seat (Palmer's Australian Party is preferencing them). The Fishing and Lifestyle (they like fishing and outdoorsy stuff) and Family First (socially conservative Christian) parties also have very good preference flows.
South Australia
Labor are in danger of losing a seat or two in South Australia in the House. Also importantly Labor are in danger of losing a Senate seat.
In 2007 South Australia elected two Labor, two Liberal, one Green and the independent Nick Xenophon to the Senate. Xenophon is a moderate centrist who will work with both major parties and draws significant votes from them both as well. The general perception is Xenophon will again win a Senate seat in his own right but it's anyone guess exactly how he will poll.
I'm confident that two Liberals and one Labor senator will be elected from South Australia. I strongly suspect Nick Xenophon will be reelected. I've absolutely no idea who will win the final two seats. They may be both from the left (one Green, one Labor if they are). They might be both from the right (One extra Liberal, one minor random party (Family First and the No Carbon Tax Climate Skeptics (guess their policies) both have great preference flows)).
Western Australia
Previously the model had rather liked Labor's chances in Western Australia. This is no longer the case. I personally suspect the model may be a little too pessimistic about Labor's chances in Perth for candidate specific reasons.
In 2007 Western Australia elected three Liberals, two Labor, and one Green Senator.
Labor struggled in Western Australia in 2010. Even a fairly small swing against them could lead to Labor being reduce to a single seat. The Greens could also potentially lose their seat despite their traditional strength in this state. However both parties will under no circumstances lose a seat each.
The Liberals should be considered very likely to retain their three seats. If Labor or the Greens were to lose a seat that seat would be most likely won by the WA Nationals (who technically aren't part of the Coalition but would be nearly as good for the Coalition). It is also possible, though markedly less likely, a minor party from the right or even the Liberals could win the last Senate seat.
Tasmania
Polling has Labor looking like receiving a huge swing against them. Labor may very well lose all of their House seats though there is still hope of saving Franklin and Lyons.
In 2007 Tasmania voted strongly for the left in the Senate sending three Labor, two Liberal, and one Green to represent them. Polling is very clear that the Liberals will be electing three senators this year. It is most likely that the Greens will receive enough of a primary vote to reelect their Senator, leaving Labor the remaining two seats. It is possible the Labor may be able to beat the Greens and send three senators again, but in my view less likely.
Territories
Labor is probably in trouble in Lingiari and isn't very likely to reclaim Solomon. Though polling in the Northern Territory is of poor quality and anything could happen.
Both Territories always elect one Coalition senator and one Labor Senator. This could change this year.
In the Northern Territory Julia Gillard (when she was Prime Minister) declared that the long-time Labor Senator from the Northern Territory was to be replaced at the election by an Aboriginal candidate. This met with a mixed response. Even a small swing against Labor could lead to the election of a AFNPP (First Nations) Senator. It's also theoretically possible a Sex party candidate could win election.
In the Australian Capital Territory the Liberals have been living dangerously close to losing their senate seat for years. This might not be the election they finally lose their seat to the Greens (though their candidate cut down the sitting senator in a "primary" challenge and is way less moderate so maybe it is).
Summary
The most likely Senatorial outcomes in my view follow;
The Coalition would appear to be a long way short of winning the five extra seats they would need to win control of the Senate in their own right. However the Left (Labor + Greens) look quite likely, though not certain, to lose at least three (net) seats and control of the Senate. The putative Coalition government will likely be able to pass legislation with the assistance of a selection of Right-aligned Senators. It wouldn't be particularly smooth sailing but it would be much easier than if the Left were to retain control.