On 18 March Tasmania will become the third of the eastern states to decide whether to give its Labor government a third term. In NSW (2003) and Queensland (2004) Labor won resounding victories – but Tasmania looks like being more difficult.

One reason is Tasmania’s electoral system. Each of Tasmania’s five electorates (the same boundaries as its federal electorates) elects five members by proportional representation. At the 2002 election, Labor won two seats in Bass and three in each of the others, for a total of 14. The Liberals won seven (two seats in Bass and Braddon, and one in each of the other three), and the Greens four (a seat in each electorate except for Braddon).

Ten of Labor’s seats can be regarded as safe – two in each electorate; they would need swings of more than 15% to be lost. Two Greens seats (one each in Denison and Franklin) are also safe. So for the Liberals to win a majority, they would have to win all of the remaining 13 seats. It’s mathematically possible, but so unlikely that most commentators are not giving it much thought.

The real interest is in whether Labor will lose its majority. The most recent poll, published in Saturday’s Mercury, has Labor on 43% of the three-party vote (down 10% from 2002), the Liberals on 34% (up 6%) and the Greens on 23% (up 4%). The pollster’s “best guess” from that is that “the ALP would get 11 seats, Liberals 7, The Greens 5, with two uncertain”, and that the two uncertain (unfortunately the story doesn’t tell us which they are) might go one Liberal and one Green.

The threat of a hung parliament may turn out to be Labor’s trump card.

If a majority Liberal government isn’t realistically possible, and since the Liberals have promised not to govern with Green support, Labor can present itself as the only party that can possibly deliver stability.

But that might not be enough to deliver premier Paul Lennon the 13 seats he needs – and if he falls short, the fun will really begin.

For much more on Tasmania, see Antony Green‘s comprehensive guide at the ABC site.