South Australia’s Opposition Leader Vincent Tarzia has unexpectedly resigned three months before the state election, marking a fourth Liberal leadership change nationally in about a month.

The move follows a year of Liberal leadership instability, with NSW, Victoria, and the ACT each installing new leaders in quick succession.

Tarzia will remain as the Hartley representative, as the party prepares to elect a new leader to keep momentum for the Hartley seat at the next election.

Tarzia will continue to serve as Hartley’s representative, and a leadership election is planned to energy the party ahead of the next vote.

The party thanked Tarzia for his leadership and said the decision was made in the best interests of his family, constituents, and the party.

Tarzia acknowledged internal polling dissatisfaction but stressed he was not pushed or mentored to quit and would support the incoming leader regardless of who it is.

Ashton Hurn, the shadow health minister and a likely frontrunner, is expected to be the new Liberal leader if she wins the leadership ballot.

Leadership vote is imminent, with Hurn viewed as the most probable replacement, and the party confirms the vote will determine Tarzia’s successor.

Tarzia described the role as demanding but privilege-filled, and said he has no regrets about his tenure as leader.

The resignation followed discussions with family and supporters, with Tarzia aiming to give the next leader a clear run into the next state election.

Tarzia rejected claims of being forced out and said there was no evidence of wholesale internal undermining.

If Hurn or another candidate wins, she would become the third newly installed female Liberal leader in a short span across Australian states and territories.