INDEPENDENT MP Geoff Brock has revealed he will support the Labor party to form minority government in South Australia.

Mr Brock joined Premier Jay Weatherill for a press conference on Sunday morning.

He told reporters he had thought “long and hard” about his decision, and had a sleepless night, but he believed it was the right choice for the state and would provide the most stable government.

Mr Brock said he had been offered positions in a Labor cabinet responsible for regional development and state and local government relations.

media_camera Out but not down. Steven Marshall managed a smile, even after this morning’s extraordinary developments. Photo: Calum Robertson

Premier Jay Weatherill said Mr Brock’s decisions “delivered certainty and stability” to South Australians.

Mr Weatherill rushed to Pt Pirie on Saturday to meet with the MP for the mid-north seat of Frome.

Mr Brock said he phoned Liberal Leader Steven Marshall yesterday morning to inform him of his decision but his call “went to message bank”.

media_camera Steven Marshall spoke to reporters in Norwood after Frome MP Geoff Brock appeared alongside Premier Jay Weatherill to announce he would back Labor to form a minority government. Photo: Calum Robertson

The agreement with Labor allows Mr Brock to remain an independent and vote “as I see it on certain issues”, Mr Brock said.

Mr Brock said his agreement was with Mr Weatherill, not the wider Labor Party, but would not say if that meant he would walk away if Mr Weatherill was removed from the leadership.

Mr Weatherill said the arrangement also included policy changes related to regional SA, small business and electoral law reform.

media_camera SA Premier Jay Weatherill on election night. Picture: Calum Robertson

He would not detail the changes or their cost.

Mr Weatherill conceded the close election result “wasn’t a resounding endorsement” of Labor but said his party going forward would “govern like we have a majority of eight” in the Parliament.

Mr Brock said he had left a message with Dr Such’s wife Lyn yesterday morning.

media_camera Independent MP Bob Such.

Mr Weatherill would not say when he expected Dr Such to make a decision on who to support or if he would side with Labor.

Liberal Leader Steven Marshall has labelled independent Geoff Brock’s choice to back a Labor government as “the wrong decision”.

Mr Marshall has not spoken to Mr Brock since the MP for Frome made his announcement that he would support a minority Labor government.

Mr Marshall missed a call from Mr Brock ahead of the announcement.

He said he listened to Mr Brock’s voice message just before the Frome MP held a joint press conference with Premier Jay Weatherill.

Mr Marshall said he spoke to Mr Brock a number of times on Saturday and was not given any indication he would make his decision on Sunday.

“I think it’s the wrong decision,” Mr Marshall said.

“I don’t think the people of Frome would be happy either.

“There is no mandate whatsoever for Jay Weatherill (from the election result).”

Mr Marshall said he would “absolutely” stay on as Opposition Leader and it was too early to talk about any changes to the parliamentary Liberal team or frontbench.

“We’ve been a very united party for an extended period of time now,” he said.

Meanwhile, Bob Such will undergo surgery on Wednesday and will take extended leave from Parliament up to two months.

Dr Such, who is currently in hospital ahead of his scheduled surgery, issued a brief statement yesterday morning.

“Dr Bob Such MP, Member for Fisher, became aware of a medical issue on Friday evening, 21 March, and will be undergoing surgery on Wednesday, 26 March,” the statement read.

“He will be taking leave from Parliament for up to two months.

“The Premier, the Leader of the Opposition, and Mr Geoff Brock have been advised.

“Please respect the family’s request for privacy.

“No further comment will be made at this time.”

Dr Such, 69, is in Flinders Medical Centre and Advertiser.com.au understands he will take sick leave that could last for months.

The exact nature of his condition has not been revealed, but it is understood he has been scheduled for surgery in coming days.

Both Premier Jay Weatherill and Opposition Leader Steven Marshall, who had hoped Dr Such could help deliver them minority government, have sent their best wishes.

The Labor Party is almost certain to win 23 seats and the Liberal Party 22 seats.

Advertiser.com.au understands neither party has spoken with Dr Such since Monday, and our reporters have been unable to contact Dr Such’s family. Flowers were dropped off at his Coromandel Valley home by taxi yesterday afternoon.

Early in the week, Dr Such — a former Liberal MP who quit the party more than a decade ago — said he had made no decision about which party to support.

However, he made it clear he felt attacked by the Liberals during the campaign and did not agree with most of the party’s policies or direction.

LEADERS OFFER SYMPATHY

Mr Weatherill said: “I am concerned for Dr Such’s wellbeing and I have extended my best wishes to his wife and offered my support. We wish Dr Such a speedy recovery and support his family’s request for privacy.”

Mr Marshall also responded, saying: “On behalf of the South Australian Liberal Party, I wish Dr Such a full and speedy recovery. I have spoken with Dr Such’s wife today and offered her and the Such family my full support. Their wishes for privacy must be respected.”

Mr Brock said he last spoke to Dr Such on Thursday.

“I didn’t really have any indication of what would happen today, he seemed fine,” Mr Brock said.

“His wife rang me earlier and apologised for him being sick and said Bob wouldn’t be able to meet with me again soon.

“I just said ‘there’s no need to apologise’. The number one thing is that Bob gets better.

“My partner, my family and I wish him a speedy recovery. I’ll just keep going about things as I have been, but the most important thing is Bob’s health.”

The news came as Labor sources confirmed Mr Weatherill had the full backing of the factions to do whatever it took to attract Mr Brock’s support, including handing him a ministry.

A senior source said the party’s full focus had swung to wooing Mr Brock even before news of Dr Such’s illness broke.

Mr Brock held negotiations with Mr Weatherill and Mr Marshall on several occasions during the week.

Earlier on Saturday, before the news about Dr Such was broken on Advertiser.com.au, Mr Brock said speculation one or both parties might offer to make him a minister in exchange for support “is all hypothetical at this stage”.

“It hasn’t been offered. Such an offer may become part of the equation and I will need to weigh up if it’s in the best interests of my electorate and the state as a whole,” Mr Brock said.

“Whether or not people are frustrated, it doesn’t matter. What I’m trying to do is get commitments down from both leaders, in black and white with time frames. If people are frustrated that it will take me a few more days, so be it. I’m not going to be pushed into a decision.”

Dr Such won his seat of Fisher in 1989 as a Liberal Party MP.

When the Liberals won the 1993 election, then-premier Dean Brown made Dr Such the further education minister.

But when John Olsen deposed Mr Brown as leader, Dr Such was moved to the back bench and lost preselection for the 2002 election. He ran as an independent and has held the seat ever since.

Between April 2005 and April 2006, he was Speaker of the House of Assembly.

At last weekend’s election, Dr Such won 59.7 per cent of the two-party preferred vote, compared to 40.3 per cent for Liberal candidate Sam Duluk.

In 2005, Dr Such was diagnosed with prostate cancer, and in 2012 told the story of his cancer treatment to tomorrowcounts.com.au.

- David Jean, Daniel Wills, Sheradyn Holderhead and Callie Watson

THE SCENARIOS

Which if Dr Such makes no decision on who to back?

Labor can still form government with Mr Brock’s support as that would give them 24 seats, the Liberals 22 and the independent Dr Such alone as the one remainder. Were Mr Brock to side with the Liberals, both parties would be able to command 23 seats in Parliament. The side that appointed a Speaker would become the opposition. It is highly unlikely either would do this, meaning another election would be on the cards. Should Mr Brock not choose a side, Labor would have a one-seat majority, but this would be tenuous given the need for them to appoint a Speaker. Another election could also likely be called if this scenario were to arise.

What if Dr Such supports Labor?

Labor can form government without Mr Brock’s support as long as the Liberals agreed to provide a voting pair for Dr Such while he is on leave. This means that a Liberal member would abstain from voting to nullify Dr Such’s absence. With Mr Brock’s support, Labor would have an even stronger grip on power.

What if Dr Such supports the Liberals?

The decision on who forms government would be up to Mr Brock. If Mr Brock chose to support Labor it could form government. If Mr Brock also supported the Liberals then Labor would have to agree to pair Dr Such while he is on leave in order for the Liberals to form a stable government.

What if Dr Such cannot return to parliament and there is a by-election in Fisher?

Based on last week’s election results, the seat of Fisher would likely go to the Liberals. In that case Liberal and Labor would have 23 seats each, leaving Mr Brock to decide who he supports to form government. Should he not make a decision, another election could be called.