James Stevens has resigned as South Australian Premier Steven Marshall's chief of staff to seek preselection for the federal seat of Sturt.

Key points: Christopher Pyne announced he was quitting seat of Sturt yesterday

Christopher Pyne announced he was quitting seat of Sturt yesterday He said James Stevens fit his criteria for a replacement

He said James Stevens fit his criteria for a replacement Mr Stevens has announced he will seek preselection for Sturt

Defence Minister Christopher Pyne announced his retirement as the Member for Sturt yesterday after 26 years in Federal Parliament representing the eastern suburbs' seat.

Mr Stevens, 35, announced his resignation in a post on his Facebook and Twitter accounts, saying it had been "an amazing six years for me in the role".

"I have decided to seek preselection for the seat of Sturt, a seat I was born in, live in, and have campaigned in for my nearly 20 years of membership of the Liberal Party," he wrote.

"No matter what transpires, I owe Steven Marshall and the Liberal Party everything for giving me the opportunity to be a part of such an amazing team."

The state Liberal Party executive opened Sturt preselection yesterday.

Nominations close on Friday.

The preselection vote will be held two weeks later.

Therese Kenny — a former adviser to Mr Pyne and a state election candidate — and Burnside councillor Henry Davis told the ABC they did not plan to run against Mr Stevens.

"[Mr Stevens] will be a formidable candidate," Mr Davis said.

Pyne all but endorses Stevens

Yesterday, Mr Pyne said Mr Stevens fit all of his criteria for a replacement and he was "a very fine individual".

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"The first criteria is the person has to be able to win and to campaign to win the seat," he said.

"Second, they have to be an effective representative of the eastern and north-eastern suburbs, that means it has to be someone from the area and who knows it well, and who has known the area for a long time, not some blow-in from outside the electorate.

"And thirdly, they have to be someone who can be a cabinet minister in an Australian Government."

Mr Stevens ran the last four Sturt federal election campaigns and is the president of the Sturt Federal Electorate Conference, which preselects candidates.

He is a former state president of the Young Liberals.

He worked with Mr Marshall at the Michell wool company before the Premier entered politics.