New state opposition leader elected in resounding vote

His withdrawal left only two contenders, Mr Tarzia and former speaker Josh Teague.

The  party's 22 MPs voted 18-4 to install Mr Tarzia, who holds the northeastern Adelaide seat of Hartley.

The 37-year-old was elected to parliament in 2014 and served in Steven Marshall's one-term government.

David Speirs had served as opposition leader since April 2022. (Abe Maddison/AAP PHOTOS)

Mr Speirs became the party leader in April 2022, replacing Mr Marshall after Peter Malinauskas led Labor to a landslide victory.

The Liberals have served just one term in office in SA in the past two decades with Labor otherwise reigning supreme.

Mr Speirs quit on Thursday, saying he had had a "gutful" after weeks of speculation over his leadership.

He said he had "made a fairly good attempt at consolidating the party, uniting the party and moving it to the future".