Voters in Adelaide's eastern suburbs will go to the polls for a third time in just a few months, with former deputy premier Vickie Chapman set to quit politics.
Ms Chapman told colleagues of her plan to quit on the same day they met to elect former environment minister David Speirs as the party's new leader.
Ms Chapman is taking leave interstate and was a notable absentee from the leadership ballot.
She declined to comment when approached by ABC News at Adelaide Airport this evening.
Mr Speirs said he did not believe the timing of her decision was personal.
"I've never had a cross word with Vickie," he said.
"We've obviously had policy discussions behind the closed doors of cabinet where we haven't necessarily been on the same page but those would be few and far between."
He said he was "sad to see her go".
"I respect that decision but we must move forward and try and heal any divisions that do remain in the party," he said.
The ABC understands Ms Chapman will not formally tender her resignation until after parliament resumes on May 3, meaning a by-election in her safe seat of Bragg cannot be held on the same day as the federal election on May 21.
Ms Chapman quit as deputy premier and planning minister and stood aside as attorney-general in November and was suspended from parliament amid an ombudsman's investigation into her decision to block a port development on Kangaroo Island, where she owns property.
Ombudsman Wayne Lines is investigating whether Ms Chapman had a conflict of interest in making the decision, and whether she breached the ministerial code of conduct.
His report is expected to be tabled in parliament in coming weeks.
First female deputy premier of SA
Ms Chapman, formerly a barrister, was re-elected last month with a margin of 18.2 per cent despite a large swing against the Liberal Party that saw Labor's Peter Malinauskas elected as Premier.
She was deputy leader to Steven Marshall from 2013 until five months ago, after previously serving in the same position from 2006 to 2009.
She was the state's female first deputy premier and attorney-general upon the Liberals' election to government in 2018.
She supported successful moves to bring in euthanasia and to decriminalise abortion, along with the unsuccessful push to allow sex work in the state.
Mr Marshall has previously said he intended to see out his term in the neighbouring seat of Dunstan.
A standalone by-election in Bragg would likely cost taxpayers hundreds of thousands of dollars.
Joint by-elections in Cheltenham and Enfield in December 2018 prompted by the resignations of former premier Jay Weatherill and former deputy premier John Rau cost $770,000.
