What would it take to trigger an early election?

It feels like longer, but just two years ago we were all searching for signs of a post-budget “bounce”, as a desperate government tried every trick it knew to make up its huge deficit (there’s that word again!) in the opinion polls. This year, we have a government with an apparently insurmountable lead, wondering whether (and if so, how) to take its chances on an early election.

The topic came to the fore this week with the alcopops tax; already rejected once by the senate, it was reintroduced on Tuesday and, if rejected again, could be a double dissolution trigger. And this week’s papers are full of speculation after Kevin Rudd last night seemed to threaten an early election if budget measures are obstructed. Grattan has written a piece today on the risks of Rudd getting too excited and calling a premature election.

First, the mechanics. Any election in the next 14 months will almost certainly be a double dissolution, because a regular half-senate election can only be held within the year before the senators’ terms expire, which is on 30 June 2011. So an early election for the lower house would mean a separate half-senate election down the track, which governments avoid at almost any cost (the last one was in 1970).

But double dissolutions also bear a time constraint: senators’ terms are backdated to the July prior to their election. So if Rudd were to somehow contrive a double dissolution election next month, another half-senate election would need to be held within two years. That means the ideal time for a double dissolution is July-August, like the last one (11 July 1987).

Also, no double dissolution can be held in the last six months of the life of the house of representatives. That rules out the last few months of next year.

For a double dissolution to be held, the senate must reject (or fail to pass, or pass with amendments that are unacceptable to the house of reps) the same piece of legislation twice, with an interval of at least three months between the first rejection and the bill’s second passage in the house of representatives. The three months for the alcopops tax expires on 18 June.

The ostensible purpose of the double dissolution provisions is to resolve deadlocks between the houses, but that’s very much a secondary consideration here. An early election might improve the government’s position in the senate slightly, but it would still depend on some combination of Greens and independents to get legislation through.

And while the subject of the double dissolution (it needn’t be just one; bills can be stockpiled) can be passed subsequently at a joint sitting if the senate is still recalcitrant, that’s a lot of work just to get a tax on alcopops.

The real purpose of a double dissolution this year would be simply to be a vehicle for an early election, to take advantage of the government’s extraordinarily strong position in the polls. That’s not something that a naturally conservative prime minister would incline to, but it must be tempting.

A poll last week found that nearly two-thirds felt the alcopops tax wasn’t a legitimate reason for an election. Since it was commissioned by the distilled spirits industry council it should be taken with a large grain of salt, but it’s not an implausible result.

A better bet for a double dissolution trigger would be the government’s electoral legislation, which the senate also rejected in March, designed to undo the Howard government’s liberalisation of the political donation rules. If Rudd’s poll numbers are still stratospheric in a month’s time, he may well look at that route: still risky and therefore unlikely, but a real possibility.

Bob Brown on Wednesday said he thought that the chance of an early election had increased from about 20% to 30% in recent weeks. I’d say that’s about right.