In short:

SA Liberal leader David Speirs has announced his resignation from the party leadership.

The decision follows recent speculation about his future as leader.

What's next?

Mr Speirs will remain in parliament as the Member for Black, in Adelaide's southern suburbs.

South Australia's Liberal leader has announced his resignation by firing multiple parting shots, saying he has had a "gutful" and no longer has the energy to continue in the role.

David Speirs, who took over the Liberal leadership from Steven Marshall in 2022 following the party's electoral defeat, today announced his decision to quit, saying a partyroom meeting on Monday morning would determine his successor.

At a media conference at which Mr Speirs did not take questions, he said he had taken the SA Liberals from the "depths of despair" and was confident the party would be left in "good stead" — but expressed reservations about internal culture.

"To be honest, I've just had a gutful," he said.

"I don't have the energy to fight for a leadership that quite frankly in the current circumstances I just don't want to pursue any more.

"I reflect, was I a bit early, was it too soon for me to lead the party, or was the party not simply ready for me to lead it?

"I thought that sort of different approach for a Liberal Party leader might be what the party was after. I guess that's just not the case."

Mr Speirs joked he would "sail off into the sunset, so to speak" but said it was still his "intention, at this stage" to remain in parliament as the member for Black, in Adelaide's southern suburbs.

He said his resignation was partly intended to give the party the "best possible" chance at the next election, saying that the 2026 poll would be a "significant mountain for the Liberal Party to climb".

"I have made the decision I just do not have the energy at this stage, or in fact the want, to continue in this role and take the party to 2026," he said.

Mr Speirs, who said he would not be attending Monday's partyroom meeting, lambasted what he described as "speculation based on speculation based on nothing" about his future.

The 39-year-old, who is originally from Scotland and emigrated to Australia as a teenager in 2002, today also portrayed himself as something of an outsider within the party's ranks.

He said he was from "a different background, a different geographical location from the party's traditional leaders".

"I was probably a different type of leader for the Liberal Party," he said.

"The party's only ever had leaders from [Adelaide's] east and from the regions.

"I think I've made a fairly good attempt at consolidating the party, uniting the party and moving it to the future. There's been significant modernisation.

"It'll be interesting to see if those ideas are forthcoming in the coming days and if a new leader is able to take the party in a different direction.

"I suspect not, because I suspect that the foundation I've put in place in terms of the party's values and the policy platform that we are starting to unroll will leave the party in reasonably good stead."

Exit follows Dunstan defeat

Questions about Mr Speirs's future in the leadership role intensified in March following defeat in the Dunstan by-election, when Labor candidate Cressida O'Hanlon claimed victory in the seat vacated by former premier Steven Marshall.

Mr Speirs took personal responsibility for the Liberal defeat, apologising to a gathering of the party faithful on the night of the poll.

"For that result, I apologise. I am really sorry that it is as difficult as it might be," he said.

In the aftermath, Mr Speirs rejected suggestions he was on "borrowed time", telling the ABC his colleagues "want me to stay as leader".

"There is no-one putting their hand up to take over the job," he said.

"I called many of my colleagues and had good chats with them, and it was a unanimous view that I should continue."

But in his resignation statement today, he said he had used the recent parliamentary mid-winter break to "reflect on my priorities" and speak with family and friends about his future.

"Ultimately, I want to spend more quality time with them," he said.

"I look forward to playing my part in supporting the next leader of the Liberal Party in offering a fresh and strong alternative government to the people of South Australia."

Opposition frontbencher Vincent Tarzia thanked Mr Speirs "his hard work as leader of the party".

"Following his announcement I’ll be talking to colleagues and focusing on helping the team to win in 2026," he said.

SA Premier Peter Malinauskas said he was "grateful" for the "professional relationship" he had maintained with Mr Speirs throughout the latter's time as opposition leader.

"I want to acknowledge his service and thank him for it," Mr Malinauskas said.

"Being leader of the opposition is a difficult job when your team is completely united, but if you've got elements within your own party that are undermining you, it does make it even more difficult again and to that extent I feel for Mr Speirs.

"I certainly wish him all the very best for his future endeavours and I hope he makes a contribution to public life in whatever he pursues in the future."

Mr Speirs was appointed Liberal leader in April 2022, weeks after Mr Marshall's government was turfed out after just one term in office.

Mr Marshall, who took over the party leadership in 2013, brought stability to the role, which following the so-called Rannslide electoral disaster in 2006, changed hands several times in quick succession amid factional rancour.

Mr Speirs's leadership also overlapped with factional tensions, which resulted in the defection of regional MP Nick McBride to the crossbench.

"[Steven Marshall] struggled at times to bridge those divides. He seemingly had done it during the COVID period, but they've re-erupted against and come back to bite David Speirs,"  Flinders University political expert Rob Manwaring said.

"He was trying to make some sort of olive branch to other parts of the wings of the party.

"Usually when a leader steps down, it's because there's a clear challenge and challenger in place, and what we haven't seen is a really clear challenge by another candidate."

No Liberal leader has won two consecutive elections in South Australia since the Liberal and Country League's Sir Thomas Playford during the 1960s.