As Labor searches for positives from the federal election result, South Australia's only marginal seat, Boothby, is looming as one of the few potential gains — but remains too close to call.

Key points: Election results in SA have largely gone as predicted

Election results in SA have largely gone as predicted Rebekha Sharkie has claimed victory over Georgina Downer in Mayo

Rebekha Sharkie has claimed victory over Georgina Downer in Mayo Greens senator Sarah Hanson-Young is likely to remain in the Senate

The seat in Adelaide's south is currently in the balance, with the lead repeatedly switching hands between Liberal MP Nicolle Flint and Labor challenger Nadia Clancy.

"We're going to have to wait and see what happens here. Boothby has always been a marginal seat," Ms Flint told supporters.

"It's close, we always knew it was going to be close."

As Labor comes to terms with a likely defeat, despite opinion polls predicting otherwise, deputy leader Tanya Plibersek was reluctant to concede defeat.

"There's a number of other seats where we look good," Ms Plibersek said.

"We're still doing very well in Boothby, for example. We've picked up Corangamite and Dunkley in Victoria."

Nicolle Flint will have to wait to find out if she has been re-elected. ( Facebook: Nicolle Flint )

Despite uncertainty over the final result, Ms Clancy arrived to a hero's welcome at her campaign function, and acknowledged a winner would likely not be determined tonight.

"Obviously everything's still a little unclear as to what things look like nationally but also here in Boothby," she told supporters.

"What we can be sure of is Labor has had swing towards us here and Boothby and that is because of every single one of you."

Sharkie declares victory over Downer in Mayo

Meanwhile, Liberal candidate Georgina Downer's latest effort to extend her family's political dynasty in her father's former seat of Mayo looks to have ended in defeat.

For the second time in less than a year, Centre Alliance MP Rebekha Sharkie has claimed victory in that seat despite a slight swing against her since the July by-election.

Ms Sharkie distributes how-to-vote cards at Mount Barker High School. ( ABC News: Claire Campbell )

Ms Sharkie indicated she would most likely support the Coalition in the event of a hung parliament — but would be seeking commitments on a range of issues.

"I recognise I have a non-Labor seat in Mayo, and I did supply confidence to the Morrison government," she said.

"But I have a long list of expectations if I need to provide any sort of support in a balance of power situation.

"We need to get money out of politics, we need to get a federal ICAC up, we need a judicial inquiry, a proper judicial inquiry into the River Murray and we need to protect our Bight."

Georgina Downer appears to have again been defeated. ( ABC News: Claire Campbell )

Opposition to drilling in the Great Australian Bight has been a major pre-election issue in South Australia, and especially in Mayo which includes several coastal communities.

Greens senator Sarah Hanson-Young looks likely to secure re-election, despite a campaign which was disrupted by an ongoing defamation case against David Leyonhjelm.

Christopher Pyne's successor James Stevens survived an early scare in the seat Sturt, after early vote counting suggested a tough contest with Labor's Cressida O'Hanlon.

"He will be comfortably returned. We've got — he's on 48.6. You don't lose from there," ABC election analyst Antony Green said.

South Australia took a largely back seat for most of the election campaign, after losing a seat during a boundary redistribution last year.

Boothby has been one of the strongest local battlegrounds, and the campaign at times became acrimonious.

Activist group GetUp! heavily targeted the Liberal-held seat, staging stunts critical of the Coalition's stance on climate change.

Ms Flint's campaign office was also vandalised with abuse.