When the South Australian election campaign began four weeks ago, the conventional wisdom was that the Rann government would lose a bit of skin, but was likely to be returned for a third term. However, the trend to the Liberals which began when Isobel Redmond became leader last July has continued to gather pace, to the extent that Labor now hopes for little more than to hang on as a minority government.

If that’s so, the composition of the lower house cross-bench will take on immense significance. This was no doubt why The Advertiser chose to conduct its latest electorate poll in the southern suburbs seat of Mitchell, rather than one of the eastern suburbs marginals on which the election was previously thought to hinge. Mitchell is a traditional Labor seat currently held by independent Kris Hanna, who in the previous term parted company with a Labor Party he deemed insufficiently idealistic.

After briefly signing on with the Greens, Hanna contested the 2006 election as an independent and scored a surprise win, credited in part to the backing he received from then state upper house member Nick Xenophon.

As the Advertiser poll makes clear, this time Hanna faces a grave threat from the resurgence of the Liberals, which perversely promises to deliver his seat to Labor. Hanna’s win in 2006 was achieved by overtaking the Liberal candidate and coasting home on his preferences, but the Advertiser survey has the Liberal vote up about eight points, a result consistent with statewide polls.

If borne out tomorrow, that would reduce Hanna to third place and have his preferences decide the seat in Labor’s favour.

While such a result would give Labor the invaluable buffer of an extra seat, the poll carries a sting in its tail. In Labor-versus-Liberal terms, the two-party result published by The Advertiser shows an anti-government swing of 10 per cent, although that reduces to 7 per cent when using the normally more reliable method of applying preference flows from the last election. It thus chimes perfectly with recent Newspoll and Galaxy figures showing Labor set to suffer a swing which, if uniform, would cost it its majority.

With little hope of turning the ship around, Labor’s hope is that the swing will not indeed be uniform. Their two most marginal seats are at the top and tail of Adelaide: Light, based around Gawler in the north, and Mawson, consisting of McLaren Vale and suburbs at the southern edge of the metropolitan area.

Labor was hopeful at the start of the campaign that its promised duplication of the Southern Expressway could salvage the latter, but the poll result from neighbouring Mitchell underscores the point that this prospect has receded. That takes care of two of the five seats Labor can safely afford to lose, assuming it doesn’t gain Mitchell.

The decisive electoral battleground thus becomes the eastern suburbs, where the next four most marginal Labor seats are all located next door to each other: Norwood, Newland, Hartley and Morialta, held by margins of 3.7 per cent to 6.8 per cent. Most observers have Norwood pencilled in as a Liberal gain, but varying degrees of ambiguity surround the remainder.

Morialta is technically the safest of the four, but that’s because Labor over-performed there in 2006 for reasons which don’t apply this time. An Advertiser poll earlier in the campaign had the Liberals 52-48 ahead, and the word from both parties is that this is about on the money.

That leaves Labor needing to hold both Newland and Hartley, about which it is respectively hopeful and pessimistic. Any further Labor losses beyond that would be a surprise. The southern coastal suburbs seat of Bright looks vulnerable with its margin of 6.9 per cent, but Labor member Chloe Fox is believed to be safe. Despite its 10.5 per cent margin, the Liberals are said to be putting more effort into the seat of Adelaide, although Labor has spent a lot of political capital keeping the electorate on side and has a locally popular member in Jane Lomax-Smith.

For the Liberals to govern in their own right, they would need to gain all the aforementioned seats and another two besides. They can be confident of gaining Mount Gambier, a conservative seat being vacated by independent member Rory McEwen. There are two other country seats which could conceivably fall their way: Frome, the Port Pirie and Clare Valley seat they lost to independent Geoff Brock at a by-election in January 2009, and Chaffey, the Riverland seat held by the parliament’s sole Nationals member, cabinet minister Karlene Maywald.

The one cross-bencher who is not in danger is Bob Such, a former Liberal who represents the southern suburbs seat of Fisher. There are schools of thought which say Mount Gambier could pass to a new independent, or that the Eyre Peninsula seat of Flinders could fall to the Nationals, but most scenarios for the new parliament involve cross-benchers we’re already familiar with.

All are keeping their cards close to their chests. Despite her association with the Rann government, Maywald is directing preferences to the Liberals, and would be mindful of the resistance the WA Nationals faced from their constituency when they were considering sustaining the Carpenter government in office. Such says he will seek the views of his constituents, having attracted 3000 responses to such an appeal when he was similarly placed after the 2002 election. Given that he serves a naturally conservative electorate, that’s unlikely to bode well for Labor.

The other independents are more specific. Brock has indicated the price of his support would be natural gas pipelines and improved water security for his electorate. Kris Hanna also says he will seek commitments to local projects, along with “detailed policy imperatives” concerning “water, democracy and pokies”.

However, both would have to consider the internal state of the parties they were dealing with: on the one hand, a demoralised Labor Party with question marks over the long-term viability of its leader; on the other, a rejuvenated Liberal Party under a leader with unchallenged authority born of a success which few were anticipating even six months ago.