Rann's end 'farcical'

South Australian Premier Mike Rann's retirement date will leave him less able to negotiate effectively on the Olympic Dam proposal to create the world's biggest mine, his political opponents say.

Mr Rann will step down as premier on October 20 to make way for popular Education Minister Jay Weatherill.

First, he hopes to finalise negotiations with BHP Billiton over the future expansion of the Olympic Dam copper and uranium mine in the state's north.

There is a "ticking clock" over those negotiations, the premier has said.

SA deputy opposition leader Mitch Williams said Mr Rann's ten-week delay before stepping down was farcical and ego-serving.

"Today we've seen the farcical end of Mike Rann's premiership," he told journalists on Monday.

"Worse still, we've seen this state put on hold for ten weeks because of Mike Rann's ego."

Mr Williams said Mr Rann's failure to hand over negotiations on the multi-billion-dollar project showed a lack of confidence in his successor.

"The BHP Billiton deal is a lot bigger than Mike Rann," he said.

"If Mike Rann has put a date on when the deal with BHP Billiton has to be signed off, that gives them a huge position of strength relative to where they should be."

SA Greens MP Mark Parnell said he's given the whip hand to BHP Billiton and the state was now held over the barrel.

"BHP can hold out for what they want, when what we need is a premier who will be negotiating for the best deal for South Australia," he said.

Labor Party stalwarts lauded their departing leader after he ended a week of leadership speculation.

Health Minister John Hill called Mr Rann `statesmanlike and dignified'.

"I think the party will now get on very well," he said.

Federal Infrastructure Minister Anthony Albanese paid his respects to Mr Rann on Twitter.

"Congratulations on providing SA with fantastic leadership on infrastructure, services, climate change and urban policy," he tweeted."