Key seats in SA election still in doubt

A former Labor minister and a potential Liberal minister still face an uncertain future as counting continues in the South Australian election.

Liberal Rachel Sanderson, who is tipped to join Premier Steven Marshall's cabinet, is ahead by 539 votes in the battle to retain her seat of Adelaide with 76 per cent of the vote counted.

She has managed to claw her way back into the contest after trailing Labor's Jo Chapley by around 100 votes on Monday.

Ms Sanderson is expected move further ahead on postal and pre-poll votes but is yet to claim victory.

"Not having a definite outcome is certainly stressful but I am very hopeful that I will be part of a Marshall Liberal government," she said on her Facebook page.

"I am currently ahead in the count with many more to count."

While in the seat of Mawson, former Labor tourism minister Leon Bignell leads Liberal challenger Andy Gilfillan by 189 votes.

Mr Bignell faces a tough challenge to keep his seat after boundary redistribution turned it from a marginal Labor seat to marginally Liberal.

While he still leads, pre-poll and postal votes are expected to favour his opponent.

If Ms Sanderson holds on in Adelaide and Mr Bignell prevails in Mawson it will leave the new Liberal government with 25 seats of the 47 seats in the next parliament.

Labor will finish on 19 and there will be three independents.

In the upper house the Liberals look set to take three of the 11 seats up for grabs, Labor at least three with two going to Nick Xenophon's SA-BEST party and one to the Greens.

The remaining seat is expected to go to either Labor or the Australian Conservatives.