Labor's Nadia Clancy has conceded defeat in the battle for the Adelaide-based seat of Boothby with Liberal MP Nicolle Flint set to be returned to Canberra.
Ms Clancy called Ms Flint on Monday to congratulate her on her election victory.
"I wish her well as she has been afforded the privilege to continue her role as your member for Boothby," she told supporters on her Facebook page.
"I did so with the humbling knowledge that this was a tight contest."
As voting continued, Ms Flint was leading her Labor opponent 51.2 per cent to 48.8 per cent on a two-party basis.
With almost 80 per cent of ballots counted, the remaining pre-poll and postal votes were expected to favour the Liberal incumbent.
On the counting so far the swing to Labor was about 1.5 per cent, but less than the near three per cent the party needed to take the seat.
Ms Clancy said Labor had run an "incredible campaign" with the party's message heard loud and clear.
"Boothby deserves better hospitals, better schools and real action on climate change.
"I promise I will remain a fierce advocate for this community which raised me, shaped me and is home to my little family."
Ms Flint is yet to officially claim victory.
