Double dissolution likely to weaken Government's Senate position, Antony Green writes

We have all heard the arguments from the Government about the need for a double dissolution election and its potential to clear out a recalcitrant and uncooperative crossbench — but not so fast, writes ABC's election analyst Antony Green.

Green has been dissecting the data and crunching the numbers for his blog with the following claims:

  • Green says there are serious questions about whether a double dissolution election will be of any benefit to the Government in securing additional Senate seats
  • The main reason is the lower quota — in a double dissolution the quota for election is only 7.7 per cent while in a normal election the percentage is 14.3
  • In a double dissolution the two biggest independent threats are Nick Xenophon and Jacqui Lambie. Glenn Lazarus and Bob Day are also in with a chance. In Queensland, Pauline Hanson would also be a possible rival for the last Senate seat
  • At a half Senate [normal] election, John Madigan is certain to lose his seat to the Liberals, the Senator Xenophon and Senator Lambie parties would not poll as well in that scenario
  • The Government could well have more chance of improving its position in a normal election, which would mean all Lower House seats and half the Senate is up for re-election. The quota for election is also higher


With the passage of Senate electoral reform and recall of Parliament for April 18, the groundwork has been laid for the Turnbull government to use the new electoral system at a double dissolution election and wipe the Senate's political slate clean.

Electoral reform has aggravated the half dozen cross-bench Senators whose terms run past the next election and through to 2020. A double dissolution would allow the government to clear out the cross bench, though who their replacements would be is not clear.

But there are serious questions whether a double dissolution would be of any benefit to the government's Senate position.

As modelling in this post shows, a double dissolution is unlikely to deliver the Coalition more Senate seats than it currently holds. The government would still need the support of up to half a dozen cross bench Senators to pass legislation.

The only real winner from a double dissolution would be South Australian independent Nick Xenophon, who would bring in two or three Senators on his coat tails.

Looking past the polls and concentrating only on the Senate's complex quota mathematics, the government's best chance of improving its Senate position would be continuing through to a normal House and half-Senate election later in the year.

In summary the government currently has 33 Senators. It is likely to return fewer than 33 seats at a double dissolution, but would probably increase its numbers to 34 seats at a half-Senate election.

There are  two advantages for the government in calling a double dissolution.

The first is that it allows an election to be held earlier, it not being possible to hold a House and Half-Senate election before August. With the trend being against the government in opinion polls, holding an earlier election is an attractive proposition.

The second double dissolution advantage is that the contentious legislation triggering the election could be put to a joint sitting of Parliament afterwards. However, that would require the government to win support from 114 of the 226 members present at a joint sitting. If the government wins only 33 Senate seats, it would need to win more than 80 of the 150 House of Representatives seats to pass legislation.

A House and half-Senate election would deny the government a chance to use a joint sitting to pass legislation. But due to the different quotas for election, the government would be more likely to increase its Senate numbers at a half-Senate election compared to a double dissolution.

Quota Changes for a Double Dissolution.

A double dissolution election returns 12 Senator per state rather than the usual six per state at a half-Senate election. It lowers the quota for election from 14.3% to 7.7%.

The lower quota means that a double dissolution election produces a more proportional outcome than a half-Senate election. The lower quota makes it easier for minor parties and independents to win election.

However, it is the change in the vote required to elect six Senators in a state that is the problem for the Coalition at a double dissolution election.

At a half-Senate election a party needs 28.6% of the vote to elect two Senators and 42.9% to elect three. A major party polling 40% of the vote would have 2.8 quotas worth of votes and at successive half-Senate elections return three of a state's six Senators, six of 12 Senators over two elections.

At a double dissolution a party needs 30.8% to elect four Senators, 38.5% for five Senators, and a higher 46.2% of the vote to elect six Senators.

A party with 40% of the vote would have 5.2 quotas of votes at a double dissolution, delivering only a certain five seats. The percentage vote that would deliver a party six Senate seats in a state over two elections would only deliver five seats at a double dissolution.

The problem for the Coalition is that it currently holds six Senate seats in three states, New South Wales, Queensland and Western Australia. Based on the results of the last two Federal elections, the Coalition would win only five Senate seats in NSW, would struggle to reach six Queensland, but would have a chance in Western Australia, though more recent polling in the west has been less encouraging for the government.

Against this, the Coalition would be certain to win extra seats in Victoria and Tasmania, but might lose a seat in South Australia, where the high level of support for the Nick Xenophon Team makes modelling very difficult.

The January to March quarterly Newspoll reported Coalition House first preference votes of NSW 45%, Victoria 41%, Queensland 44%, WA 47% and SA 41%. These figures overstate Coalition Senate support, first because parties have a lower vote in the Senate compared to the House, and second because there has been a slide in government poll ratings since the start of the year.

Any drop in the above poll numbers numbers and the Coalition could only win five Senate seat in the three states where it currently has six Senators. It would be a Pyrrhic victory for the government if it called a double dissolution and found itself afterwards with a weaker Senate position.

At a half-Senate election under the new electoral system, the Coalition would probably retain its three seats in NSW, Queensland and Western Australia, and would be certain to gain a seat in both Victoria and Tasmania.

The two biggest independent threats to the government's position at a double dissolution , Nick Xenophon and Jacqui Lambie, would not face the electorate if a half-Senate election were held. Xenophon's team could still take the Liberal Party's third South Australian Senate seat a half-Senate election, but the Liberal Party's potential third Tasmanian seat would be under less threat from the Jacqui Lambie Network without her on the ballot paper.

Labor and the Greens

The table below sets out the current composition of the Senate.

Current Party Composition of the Senate by State
State Coalition Labor Greens Others
New South Wales 6 4 1 1
Victoria 4 4 2 2
Queensland 6 4 1 1
Western Australia 6 3 2 1
South Australia 5 3 2 2
Tasmania 4 5 2 1
Australian Capital Territory 1 1 .. ..
Northern Territory 1 1 .. ..
Australia 33 25 10 8

At a double dissolution the quota for one seat is 7.7%, for two seats 15.4%. As outlined below, the Greens would probably hold their two seats in Victoria, WA and Tasmania at a double dissolution. The lower quota would aid the Greens in holding their single seats in NSW and Queensland. At a double dissolution the Greens would have little chance of returning two seats in South Australia, meaning defeat for one of the party's two Senators, Robert Simms and Sarah Hanson Young.

At a half-Senate election the Greens would be defending their record result in 2010 when the party won seats in all six states. Senators in Victoria, WA and Tasmania would be easily re-elected. Under the new electoral system the party would be in a race with the third Labor candidate for the final seat in both NSW and Queensland. There would be a very complex race for the final seat in South Australia due to the popularity of the Nick Xenophon Team.

So the Greens go into the election with 10 seats, six elected in 2010 and four in 2013. The Greens would probably finish with nine at a double dissolution, most likely nine at a half-Senate election, with 8 or 10 Senators being possible.

Labor has only 27 Senate seats at the moment, having had a dismal result in 2013, winning only 10 of the 36 Senate seats on offer. At a double dissolution the party should easily achieve the 30.8% it needs to win four seats in all states except South Australia (the Xenophon factor again), and should win five seats in most seats. Labor would gain seats at a double dissolutuon.

A half-Senate election would be more complex for Labor. The only state where Labor won three seats in 2010 was Tasmania, and the party's island fortunes have withered substantially in the last six years. At a half-Senate election it is likely that the Liberals would take a Tasmanian seat from Labor with the Greens winning the final seat.

At a half-Senate election Labor would struggle to win a third seat in any of the mainland states, its best chances being the contest for the final seat against the Greens in NSW and Queensland.

So in summary Labor would probably gain seats at a double dissolution, but be returned with the same and possible fewer seats at a half-Senate election.

The Cross-Bench  

The table below shows the eight cross bench members.

Cross Bench Senators 2016
Face Election State Candidate Party % Vote
2016 VIC John Madigan John Madigan's Manufacturing and Farming Party (ex-DLP) 2.3
2019 NSW David Leyonhjelm Liberal Democratic Party 9.5
2019 VIC Ricky Muir Motoring Enthusiast Party 0.5
2019 QLD Glenn Lazarus Glenn Lazarus Team (ex-PUP) 9.9
2019 WA Zhenya Wang Palmer United Party 5.0
2019 SA Nick Xenophon Nick Xenophon Team 24.9
2019 SA Bob Day Family First 3.8
2019 TAS Jacqui Lambie Jacqui Lambie Network (ex-PUP) 6.6

 Note: The % vote for Zhenya Wang is taken from the 2013 Senate election. His party polled 12.3% at the April 2014 re-election.

At a double dissolution election, the Nick Xenophon team would be certain of electing three or four Senators in South Australia. It may have hopes of polling well in other states as well.

Jacqui Lambie would have a very strong chance of election at a double dissolution election, as would Glenn Lazarus in Queensland. Bob Day would also have a chance given Family First have a relatively consistent 4% of the vote in his state.

The new electoral system will be a major impediment for other minor and micro parties. Under the old system with group voting tickets, micro-parties were able to nominate in droves and then swap preferences. Group voting tickets made it advantageous to stand as many micro-parties as possible to make it harder for voters to find the parties they did know, and to herd voters into voting for the tickets above the line.

Under the new system, standing a multiplicity of parties will only fractionalise the micro-party vote which will then tend to exhaust as preferences.

Under the new electoral system, it will be to the advantage of well known candidates, such as Glenn Lazarus or Jacqui Lambie, for there to be fewer parties on the ballot paper. The minor parties that already poll above 2% will be advantaged if the proliferation of micro parties polling below 0.5% are absent from the ballot paper. The new electoral system advantages parties with first preferences where the former system allowed preference tickets to play a greater role.

At a half-Senate election, the only cross-bench member up for election, Victoria's John Madigan, is certain to lose his seat to the Liberal Party. The Nick Xenophon team would probably gain a seat in South Australia, though the party is likely to poll less well than in 2013 as Nick Xenophon himself will not be facing election. The Jacqui Lambie Network would also be an outside chance in Tasmania, but that might depend on ballot draw and other micro-parties choosing not to contest.

The lower quota at a double dissolution means that most micro parties will still roll the dice in trying to win election. The higher quota at a half-Senate election combined with the new electoral system means that there are likely to be fewer candidates and parties on the ballot paper at a half-Senate election.

New South Wales

Current Senators: 6 Coalition, 4 Labor, 1 Green, 1 Liberal Democrat

Facing Half-Senate Election: 3 Coalition, 2 Labor, 1 Green


The normal NSW Coalition Senate vote  is around 40%. Since 1984 the lowest Coalition vote was 34.3% in 2013 when voters were clearly confused by the presence of the Liberal Democrats in column A of the ballot paper. Only three times has the Coalition approached 5.4 quotas or 41.4% of the vote, with 5.4 quotas in 1996 on John Howard's election to office, and twice more under John Howard, 44.8% (5.43 quotas) in 2001, and 44.1% (5.74 quotas) in 2004.

You would expect the Coalition vote to improve on its 2013 result, but getting above the 42% level to have a chance for a sixth seat looks problematic. Preferences with the Christian Democrats may be important in delivering either a sixth Coalition seat, or Coalition preferences delivering a seat to the Christian Democrats.

Labor's NSW vote used to be higher than the Coalition's but has slipped in recent years. It seems certain that Labor's vote will rebound from its dreadful 31.6% (4.1 quotas) in 2013. Only in 2013 and 2001 has Labor's vote fallen short of 4.5 quotas, so any return to a more normal level of Labor voting would deliver the party five Senate seats.

The Greens would be certain of returning one Senator, but the party's highest vote in the past was 10.7% in 2010, 1.39 quotas. 

At a half-Senate election the Coalition would most likely win three seats, Labor two, with the final seat a contest between the third Labor candidate and Green's Senator Lee Rhiannon.


Current Composition: 4 Coalition, 4 Labor, 2 Green, 1 John Madigan, 1 Ricky Muir

Facing Half-Senate Election: 2 Coalition, 2 Labor, 1 Green, 1 John Madigan


At a half-Senate election the Victorian result would be relatively straight-forward. The Coalition's vote would be at around its long term average of 40% and elect three Senators, gaining a seat at the expense of John Madigan. Madigan was elected as a DLP senator from 2.3% in 2010 when the Coalition's support fell to a historically low 34.4%.

Labor's vote has slipped below 40% more regularly in recent years as the Green vote has grown. The Green vote has been above 10% at the last three Victroian Senate elections. If Labor's vote is below 38% and the Greens above 10% the Greens would be favoured to win the last seat. If the Greens poll 10% then Labor's vote must be above 38% to have a chance of winning three seats. The most recent quarterly Newspoll had the Greens on 15%, and with the party's usual Senate boost, that would easily be enough to win the final seat.

At a double dissolution election both Labor and the Coalition would likely finish with five seats, and on the quarterly Newspoll the Greens would win two seats.


Current Composition: 6 Coalition, 4 Labor, 1 Green, 1 Glenn Lazarus

Facing Half-Senate Election: 3 Coalition, 2 Labor, 1 Green



The Coalition's support is consistently above 40% in Queensland. The only time it fell below 40% was in 1998 when One Nation won the final Senate vacancy. The Coalition returned to running joint Senate tickets in 2007 and merged to form the LNP in 2010. At a half-Senate election the Coalition would easily return its three Senators, Labor would elect two, and the third Labor Party candidate would be competing with Green's Senator Larissa Waters for the final seat.

At a double dissolution the Coalition might be reduced to five seats while Labor would easily return four Senators, might elect a fifth, and the last seat would be a contest. The Coalition would find itself competing with Glenn Lazarus and Pauline Hanson for the last seat. Hanson has easily polled 4% in her own right in the past in Queensland. She has returned to her One Nation origins and will be the Pauline Hanson's One Nation candidate in Queensland.

Western Australia

Current Composition: 6 Coalition, 3 Labor, 2 Green, 1 Palmer United

Facing Half-Senate Election: 3 Coalition, 2 Labor, 1 Green



Western Australia is the only state where a significant National Party ticket runs in competition to the Liberal Party. Despite this the Liberal Party has consistently polled above 40% at half-Senate elections and would easily elect three members at a half-Senate election in 2016. The half-Senate numbers would be completed with two Labor and one Green Senator. This would be a no change position from 2010.

At a double dissolution election, the separate National ticket could be more important. The positition of the Liberal Party in the west has subsided owing to the state of the post-mining boom economy. If the Liberal vote slips it would only win five seats at a double dissolution. The Nationals polled 5% in 2013, a good chance of being turned into a seat at a double dissolution, especially if talks about recruiting former state leader Brendon Grylls prove fruitful.

Labor should win four seats at a double dissolution, up from three in the current Senate. The Greens polled 9% in the most recent quarterly Newspoll, but this would probably be higher in the Senate, and that could give the Greens two seats. The Greens have two high profile Senators who would add to the Green vote.

South Australia

Current Composition: 5 Coalition, 3 Labor, 2 Green, 1 Xenophon, 1 Family First

Facing Half-Senate Election: 3 Coalition, 2 Labor, 1 Green



The phenomenon that is Nick Xenophon makes picking the South Australian result very difficult. Based repeating the party votes from 2013, the new electoral system would deliver 2 Liberal, 2 Labor and 2 Xenophon Team members at a half-Senate election. However, as Xenophon himself would not be contesting a half-Senate election, the vote for his team may be lower. The more likely result would be 2 Liberal, 2 Labor, 1 Xenophon with the last spot a four way race between Liberal, Labor, Xenophon and the Greens.

A double dissolution would be just as difficult to pick. With Xenophon on the ballot, his team would win 3 or 4 seats, the Greens would have a chance, as would Family First, and the balance of seats would be won by Labor and Liberal. It is very difficult to pick.

Equal representation by state in the Senate does leave the balance of power more open to the idiosyncratic politics of the two smallest states, South Australia and Tasmania.


Current Composition: 4 Coalition, 5 Labor, 2 Green, 1 Jacqui Lambie

Facing Half-Senate Election: 3 Labor, 2 Coalition, 1 Green 


In both 2007 and 2010 Tasmanian returned three Labor, two Liberal and one Green Senator. Those Tasmanian numbers are entirely responsible for why the Gillard government faced less problems in the Senate than it did in the House.

Labor's political fortunes have reversed since 2010, with the party losing state office in 2014 and wining only one House seat at the 2013 Federal election. It is most likely that at a half-Senate election, the Liberal Party would gain a seat at Labor's expense. The Greens would easily retain their current seat. The Jacqui Lambie Network would poll less well at a half-Senate election compared to a double dissolution as Lambie herself would not be a candidate.

A double dissolution would be very difficult to predict. The quota for election would be only around 25,00 votes, fewer than the votes polled by four of the winning House candidates in Tasmania at the 2013 election.

At a double dissolution, the long term averages point to both the Labor and Liberal Parties being certain of four seats each, the Greens two, with the last two seats up for grabs. One of these seats would go to the higher polling major party, probably the Liberal Party, and the last seat would be open for a minor party, with the Jacqui Lambie Network highly likely to win with Lambie on the ballot paper at a double dissolution.

In the last three decades the Liberal Party has only polled above 40% in Tasmania three times, 44.1% in 1990 when the Field Labor government was deeply unpopular, 42.3% on the defeat of the Keating government in 1996, and 46.1% on the back of Mark Latham's forestry announcement in 2004. On that basis it seems hard to believe the Liberal Party can win six seats at a double dissolution.

If the Tasmanian power system falls over between now and election day, Tasmania would become one of the election's biggest wild cards.

Source: Antony Green ABC News

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