Three years ago South Australia was barely a blip on the national electoral radar.

But now the confluence of harsh economic circumstance and a political X-factor threaten to make the state a wildcard on election night.

Nation-leading unemployment, the collapse of traditional manufacturing industries like the car industry and the future of submarine, ship and steel making have dominated the political debate in South Australia.

It is no surprise that the canny X-man, independent senator Nick Xenophon, has latched onto these issues to propel his campaign.

Senator Xenophon's decision to run candidates in all 11 of South Australia's House of Representatives seats sent a chill through the major parties.

Suddenly, instead of fearing the loss of one western suburbs seat — Hindmarsh — the Liberal Party feared losing several others — including Christopher Pyne's eastern suburbs stronghold of Sturt and former minister Jamie Briggs's hills-based seat of Mayo.

The threatened emergence of a genuine third-party force also has Labor nervous, according to University of Adelaide Professor of Politics Clem Macintyre.

"Seats like Adelaide and Makin for Labor are ones that the Liberals would be looking at if they can benefit from the flow of preferences from a Xenophon candidate," he said.

"But equally, they need to be defending seats like Sturt and Boothby and potentially Mayo, which until the change of prime ministership seven months ago looked like they were real problems for the Liberal Party."

House of Reps a different ball game for Nick Xenophon Team

While Senator Xenophon famously outpolled Labor on first preference Senate votes last election, Professor Macintyre is not sure that will translate into House of Representatives seats.

"I'm not sure he can win any of those seats but he may well be a game changer in terms of the flow of preferences to the major parties," Professor Macintyre said.

And there lies the delicate dance for the Liberal and Labor parties.

They will need to campaign against the Xenophon candidates to guarantee they finish ahead of them, yet at the same time, they will be appealing for the Xenophon team's preferences.

"If the Xenophon candidates are able to pick up 10, 15, at a pinch even 20 per cent in some of the House of Representatives seats, then that may mean that parties like the Liberals in Sturt and Labor in Adelaide will need a flow of preferences to hold those seats," Professor Macintyre said.

"So they will need to have some very interesting conversations with the Xenophon team.

"And for its part, Xenophon will be in a position where they might be able to negotiate an exchange of preferences with one or more of the major parties, with a view to picking up a flow of preferences in the Senate."

If you think that all paints an uncertain picture in the House of Representatives, the story is just as complicated in the Senate.

Forecasting SA's Senate seats difficult

A double dissolution coupled with changes to Senate voting practices are expected to give Senator Xenophon some advantage.

He may get two, or even three running mates elected on his ticket.

But there are also big uncertainties — can Family First Senator Bob Day survive the demise of group ticket voting? Can newly appointed Greens senator Robert Simms survive the Xenophon tide? How will the Liberal and Labor parties sort out their running order?

Professor Macintyre said in this election, prognosticators trying to foretell the South Australian Senate story should tread carefully.

"If a party's negotiating preference deals in the Senate, they can no longer be as confident that the automatic flow of preferences that was the case up until this change of rules will take place," he said.

"So I think we're in a new field and watching how the parties respond to that and the deals that they do will be one of the most intriguing parts of the election."