Former foreign minister Alexander Downer says he still has no intention of running for the leadership of the South Australian Liberal Party.

The state's Opposition Leader Isobel Redman quit the Liberal leadership on Thursday, citing ongoing leadership speculation and disunity for her decision.

There had been speculation Mr Downer was considering a run at the leadership, but the senior Howard government minister has repeatedly denied he was planning a return to politics.

Mr Downer on Thursday said his position hadn't changed whatsoever following Ms Redmond's resignation.

"I have no plans at all to enter the state parliament," he told reporters outside the National Press Club in Canberra.

He said it was entirely a matter for the SA Liberal Party to choose their new leader, with a vote expected on Monday.

"I won't be a candidate. I'm not a member of the state parliament, I don't have any plans to enter the state parliament."

Whoever is elected the new party leader would have his full support, he added.