Today there’s an opinion poll with a difference — Roy Morgan Research has released a poll of Senate voting intention, showing the Greens set to take the balance of power. That’s no surprise, but there’s a surprise in how easily they would do it — electing seven senators, one in each state plus the ACT, taking their total to 10. Labor would have 33 or 34 and the Coalition 31 or 32.
That’s not an impossible result, but the preference flows make the Greens’ task in New South Wales and the ACT very difficult. Most observers think they won’t win more than five seats unless they can secure a big increase in their primary vote. And that’s just what Morgan is suggesting, with a Greens vote of 15.5% nationwide, a swing of 6.5% since the 2007 election.
There are two reasons to treat that number with a lot of scepticism. First, the Greens vote tends to be softer than that for the major parties — it has a habit of ebbing away before election day. That’s particularly likely here, since polling in the smaller states was conducted over June and July, and so would be influenced by the big spike in the Greens vote in the late Rudd period, since largely dissipated. Sure enough, it’s those states where Morgan finds the biggest swings: 10% in South Australia and 8.7% in Western Australia.
The second reason is not specific to the Greens — it’s the fact that Senate polling is generally quite unreliable. As I explained before the last election, “when people are asked a poll question about the Senate, they think about the Senate separately”. But when they get to the polling booth they’re more likely to just take the how-to-vote card of one of the big parties, and vote the same way for both houses.
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That’s why Senate-specific polls usually overstate the vote for minor parties. It’s true that the minors (except Family First) do better in the Senate than in the House of Reps, but not that much better. In a similar phenomenon, polls also overstate the number of people who vote below the line: a survey a few years ago had 20% claiming to do so, but the real figure is about 3%. Voters don’t like admitting to pollsters that they just do what they’re told.
But having said all that, Morgan’s numbers are broadly consistent with what polls for the lower house have been saying. And it should be pointed out that their last Senate poll before the 2007 election, in contrast to the usual pattern, got the Greens result exactly right (although it overstated Labor’s vote and understated the Coalition’s).
If that happens again, there’s going to be a big Greens contingent in the new Senate. And even if it doesn’t, it’s very hard to see them not winding up with the balance of power.