The federal government has sought to head off the political and economic damage from the demise of the car industry by spending billions of dollars on defence projects based in SA.

At the same time, the prime minister's been a harsh critic of the Weatherill government's failure to "keep the lights on" and used SA as the ultimate example of how Labor combines "ideology and idiocy" when it comes to climate and energy policy.

At the launch of the SA Liberals' campaign on February 4, Mr Turnbull sought to weave together his economic plan, including company tax cuts, and the energy issue.

"We want South Australian businesses to have the confidence to invest in this state, knowing that energy is affordable and reliable and the taxes they are paying make them competitive with businesses elsewhere in the nation and around the world."

Federal Labor has been campaigning on similar issues, but from a different angle.

Labor's Nick Champion, who hails from SA, says the shipbuilding workforce is "constantly under pressure" due to redundancies and needs a national authority to co-ordinate the sector's growth.

The closure of the car industry continues to resonate as a symbol of the failure of the coalition government to support manufacturing.

And federal cuts to school funding are finding listening ears in the electorate.

As well, the federal parties have been jousting over GST revenue, as Western Australia pushes the Turnbull government to change the formula for its distribution.

Labor has been bandying about a possible $600 million cut in revenue, while the prime minister insists he is waiting for an independent report later in year before making any decisions.

Both Labor and the Liberals fear the prospect of a hung parliament, which could make future negotiations with the SA government difficult and potentially expensive for the federal budget.

However, former senator and now SA-BEST leader Nick Xenophon's strong support in his home state makes this (or even an SA-BEST win) a likely prospect.

Mr Champion described the worst-case scenario as a "shattered, divided and useless Liberal Party losing so many seats to the Xenophon team that Mr Xenophon, a bit like the dog that chases the car and one day catches it, becomes premier of the state".

Australian Associated Press