Oz Politics Blog

The next half-Senate election must occur between August 2007 and May 2008. As there is likely to be a House of Representatives election during this time, the two elections should occur concurrently.

Six of the 12 senators for each state are elected every three years, for a term of six years. The two senators for each of the two territories are elected concurrently with the elections for the House of Representatives. The terms for the Senators from the territories is for the life of the House of Representatives.

A Labor win in 2007

If Labor wins the next election, it will face a Coalition dominated Senate for its first budget, as the new senators for the states will take their seats from 1 July 2008. (I am assuming that the territories will each return a pigeon pair of 1 Coalition and 1 Labor Senator. This is the most likely outcome, although it is not beyond possible for Canberra to return two left of centre senators. If the Senate primary vote for the Coalition drops by a touch over four points, the second ACT senator would be decided on preferences.)

The Coalition holds currently 39 of the 76 Senate seats. Whereas in government this is a bare majority of 50 per cent plus one, in opposition it would give the Coalition an effective majority of two. Under the Australian Constitution, when the Senate votes are equal the question passes in the negative.

A Labor Government may even face a Coalition dominated Senate for its first term, if the Coalition manages to pick up three Senators in five or more states.

The more likely scenario, should Labor win government, is that it would face a hostile Senate where the Greens (and/or Family First) hold the balance of power from 1 July 2008.

Consequently, if Labor wins the 2007 election, I would give it better than even odds of calling a double dissolution election sometime in 2008, but more likely 2009 or the first half of 2010.

Interestingly, these numbers would also create an incentive for Labor states to be tardy in filling any Coalition casual Senate vacancies that might arise. Because, for the duration of the vacancy, the Labor Federal government may have the Senate numbers it otherwise would not.

A Coalition win in 2007

If the Coalition wins government at the next election, it is fairly likely to win three senators in each state (ie. it is likely to get more than the 42.86 of the two party preferred vote needed for the three quotas). However, if the Coalition (say) only gets two senators in one state, it would only have half the Senate vote, and would need the support of the Greens or Family First to pass legislation (because tied votes pass in the negative).

On balance, under a Coalition government, its Senate majority is likely to continue until 30 June 2011.

The current Senate

The current state of the Senate is as follows.