Labor insiders consider Rau extremely vulnerable to a raid by Nick Xenophon’s fledgling party, with high-profile Port Adelaide Enfield councillor Carol Martin campaigning strongly in the inner-northern suburbs seat.

Rau held the seat by a comfortable 8.2 per cent margin in 2014, but that was whittled back to 6.2 under the boundaries redistribution, and Enfield is now considered one of SA Best’s prime Labor targets.

Parties have been feverishly working on preference deals over the weekend, ahead of today’s final lodgement of candidates with the state Electoral Commission.

But in a devastating blow to Rau’s hopes, the Greens are not budging from their insistence that they cannot direct Greens voters to preference him ahead of SA Best – citing a range of policy areas in which the Attorney-General is “anathema” to their values.

“We’ve said we’re not preferencing John Rau,” Greens MLC and Upper House hopeful Tammy Franks confirmed to InDaily.

“We’ve got an enormous policy list of things we have a problem with his track record on.”

Foremost of those was his move to suspend planning laws before the last election, with the Greens outspoken critics of the Planning Minister’s plans for higher density urban infill.

Rau also got the Greens’ noses out of joint when he raised candidate nomination fees for elections to $3000, with the minor party fighting a rearguard action to bring it back down to $1000.

Franks also cited the sluggish pace of state industrial manslaughter laws and noted that at a recent heritage forum Rau’s name was “roundly booed” whenever he was mentioned.

Labor is standing firm in negotiations with party powerbrokers, fearing Rau will lose his seat without the Greens preferences. The minor party garnered more than 8 per cent of the primary vote in Enfield in 2014.

But the best the ALP appears to be able to hope for is that the Greens run an open ticket in the electorate, with the worst – and most likely – case a preference card favouring SA Best above the Deputy Premier.

Franks insists Rau’s brand is on the nose, and not just in his own seat.

“The Labor Party just don’t get it… John Rau absolutely killed their chances in Adelaide [in 2014] and will again,” she said.

“Greens supporters aren’t going to be willing to hand out ‘How To Vote’ cards with John Rau being given preferences from us.”

Insiders fear Labor is willing to “burn the village” to save their deputy leader, which could compromise broader preference arrangements with the Greens. It’s understood the minor party is willing to preference Labor ahead of SA Best in the Liberals in around 20 seats and run an open ticket in all other seats but Enfield.

InDaily has been told there were two other seats in which the Greens had threatened to preference against Labor, but it’s understood they since agreed to an open ticket in both. Franks confirmed this but would not disclose which seats they were.

However the Greens – for now – appear unwilling to blink on Enfield.

“SA Best have put up a reasonable candidate, so the people of Enfield – who have been treated with contempt – will have a real option,” Franks said.

Rau told InDaily the Greens’ move “would be unhelpful”, but insisted: “I don’t think it’s finalised.”

“I don’t think those things have been sorted – the conversations are occurring,” he said.

“I understand that they for some reason were saying that, but whether that’s the final position, I don’t know.

“Obviously having a preference is better than not, but they haven’t communicated anything to me.”

Asked whether the Greens directing votes to SA Best instead of him could be a decisive impediment, he said: “How many of their voters follow their ‘How To Vote’ cards I don’t know, but it certainly wouldn’t be helpful.”

Asked about his chances in Enfield more broadly, Rau said: “I don’t take anything for granted – I don’t think anyone can in this election.”

“There’s two completely different elections going on,” he said of the unusual three-cornered contest.

The Greens seem likely to run an open ticket in the South-East seat of Mount Gambier, where the Liberals and independent Troy Bell are committed to a 10-year fracking moratorium and where Labor’s brand is on the nose after the sell-off of the region’s forestry assets.

But the Greens’ endgame is the battle for the Upper House, with Franks likely to be locked in a do-or-die battle with Australian Conservatives incumbent Robert Brokenshire.

It’s expected Labor, the Liberals and SA Best will each snare three of the 11 Legislative Council seats, with either the Liberals or SA Best picking up a fourth – leaving the minor parties to scrap for the final vacancy.

If that scenario eventuates, the Greens appear better placed to snare it, as they are running in more Lower House seats – which usually bolsters a party’s Upper House vote – and are polling above Cory Bernardi’s fledgling Conservative outfit.