The Liberal Party has conceded defeat in the South Australian state seat of Dunstan, four days after voters went to the polls for a by-election triggered by the departure of former premier Steven Marshall.

The gap between the party’s candidate Anna Finizio and Labor’s Cressida O’Hanlon narrowed significantly as pre-poll and postal votes were counted this week, but the trend was not strong enough for the Liberals to retain the seat.

In a statement, Opposition Leader David Speirs said he had rang Premier Peter Malinauskas to congratulate him on his party’s victory, and thanked “Anna for her tireless work on the campaign.”

“She was a positive and energetic candidate who truly reflected the community she was wanting to represent,” he said.

“Dr Finizio comfortably won the primary vote but unfortunately the preference flow has ultimately seen us fall short by a few hundred votes.”

With most of the votes now counted in the electorate in Adelaide’s inner east, the Labor Party has gained Dunstan with 50.8 per cent of the two party preferred result.

Ms O’Hanlon leads by 345 votes.

Both major parties saw their primary vote decline.

Labor’s first preference vote was down 3 per cent, the Liberals dropped 3.2 per cent, while the Greens saw a 5.5 per cent swing to it compared to the 2022 state election.

In a statement, Anna Finizio congratulated Cressida O’Hanlon on winning the seat, and thanked the people of Dunstan.

“Every minute at your doorstep, inside your small business and out with you in the community was a privilege,” she said.

“While this was not the outcome we had hoped for, I want to thank all my supporters and our volunteers for their incredible efforts during this campaign.”

Liberal candidate, Anna Finizio, has congratulated Labor’s Cressida O’Hanlon on her victory in the seat of Dunstan.(ABC News: Che Chorley)

As early counting on Saturday night showed a swing towards the Greens, and to Labor on a two-party-preferred basis, Liberal leader Mr Speirs admitted the seat would be “exceptionally difficult” for his party to hold.

Labor stopped short of claiming victory but Mr Malinauskas said Ms O’Hanlon was on the “verge” of a “pretty remarkable” win.

Labor has stopped short of claiming victory in seat of Dunstan.(ABC News: Che Chorley)

While the Greens’ proportion of first preferences declined slightly since Saturday, the party’s candidate Katie McCusker had performed strongly.

“I picked up in the pre-poll process that there was a surge in the Greens’ [vote],” Mr Speirs said.

Greens candidate for Dunstan, Katie McCusker, said voters have rejected the politics of the major parties.(ABC News: Che Chorley)

Liberals leadership speculation

Before polls closed on Saturday, Mr Speirs said the result would partly be “a judgement on myself as leader of the party”, but has committed to remaining in the role.

“I canvassed many of my colleagues over the last 48 hours since what is clearly not a good result in the Dunstan by-election for our party and my colleagues were firmly in support of me continuing in this role,” he said.

David Speirs says he will continue as leader of the SA Liberals following the Dunstan by-election result.(ABC News: Rory McClaren)

“We’re very unified in the state team. If I didn’t think I was the right person, I’d walk away.”

The campaign between the two major parties was characterised by acrimony, with the Labor and Liberal parties trading accusations about their candidates’ business and political backgrounds.

Posted , updated