It comes after the Liberal Party itself proposed splitting the city of Port Augusta in the safe seat of Stuart – held by Energy and Mining Minister Dan van Holst Pellekaan – across three regional electorates as part of a major redraw of the electoral map.

The Electoral Districts Boundaries Commission – which sits every four years to update the state’s 47 lower house seats – appears to have Port Augusta in its sights, holding a special public hearing in the city just last week.

That was spurred in part by a supplementary Liberal submission last month, which proposed shifting the “part of the Port Augusta City Council area west of the Joy Baluch Bridge from Stuart to [Labor-held] Giles” and the Kimba District Council area into neighbouring Liberal-held Flinders.

This would address flagging population numbers in those seats which threatens to leave them short of the required electoral quota.

However, it appears likely to prompt a chain reaction of accompanying changes that could see the commission shift Port Pirie – the industrial heart of Brock’s seat of Frome – into Stuart.

Brock is a former Port Pirie mayor who won Frome narrowly in a 2009 by-election before holding it comfortably at subsequent polls, later helping Labor retain Government in 2014 by joining Jay Weatherill’s cabinet.

Of the prospect of Port Pirie and Port Augusta being merged in a single seat, he told InDaily : “Obviously if that eventuates – and I don’t know where it’s going to finish up – I’d be disloyal to my own personal community if I ran in an electorate that doesn’t include Port Pirie.”

He said he didn’t like the proposal and had “built up a good knowledge” of his broader electorate, but “I couldn’t run for parliament if it’s not in my own hometown”.

“I’d then have to run for the new proposal which would include the Port Pirie portion of Port Augusta, and some other areas,” he said.

At last week’s hearing Tom Besanko, the counsel assisting the Commission, suggested the panel was seriously considering such a move.

“The Commission would be particularly assisted by submissions in relation to the possibility of moving Port Augusta West into the district of Giles to boost elector numbers in Giles, with a portion of the south-west of Giles moving into Flinders to boost elector numbers there and the eastern part of Port Augusta remaining as the urban centre of Stuart and the gateway to the north and the north-eastern part of the State – but being combined with Port Pirie, with Frome becoming a district base primarily in the Clare Valley,” he said.

Besanko noted that “various proposals that have been put to the Commission all involve substantial change which will affect a material number of people living in these communities, particularly Port Augusta”.

He said while the Commission “has not made any decisions… I stress that the point has now been reached where changes have to be made”.

“It appears that the only way to address the issue caused by the very low elector numbers in Flinders, Giles, Stuart and Frome, is by making changes involving Port Augusta.”

Van Holst Pellekaan did not comment today, saying he would await the draft boundary redistribution, due next month.

However, he told last week’s hearing he opposed his party’s proposal for his seat.

“The idea of splitting any regional centre between two electorates is a bad one,” he said.

“It’s really just not a practical thing to think that… somebody could represent the east or the west side of a regional centre: MPs would do the best that they could for the entire town, constituents would go to whichever MP they preferred, or both, for representation.

“There isn’t an issue I can think of that’s really just a west of Port Augusta issue that doesn’t affect anybody in the east or vice versa, and I’m sure the same would be true in Port Pirie and Whyalla and every other regional centre.

“So, I don’t support that idea.”

He also rejected “the idea of putting regional centres into the same electorate, because that devalues the representation that those cities have”.

Brock concurred, saying: “My concern is the three Upper Spencer Gulf cities would only have two representatives in state parliament.”

“I know there’s a quota issue but, democratically, the people of those three cities currently have three members of parliament – irrespective of which side of politics they’re on,” he said.

“If they go forward with this, the three Upper Spencer Gulf cities would only have two representatives…

“I think it’s an insult to Port Augusta, their proposal to split it in two.”

It comes as the Liberal Party also considers changes of its own to the state’s electoral act, with InDaily revealing yesterday the introduction of Optional Preferential Voting was a key reform on the table.

Brock noted that he would not have been elected in the first place under such a system – which strongly favours the candidate with the highest primary vote – because he won with a strong flow of preferences that nudged him narrowly into second place, triggering an avalanche of further preference flows to gain the seat.

Political insiders have suggested the move would strongly benefit the Liberals, given the recent demise in SA of minor parties with appeal to centrist and conservative voters, including Family First, the Australian Conservatives and Nick Xenophon’s SA Best.

The strongest minor party likely to snare major party votes is the Greens – which traditionally preferences Labor.

But sources say the move could also have a knock-on effect for future boundaries commissions, which are charged to redraw the electoral map based on the statewide vote.

Optional preferential voting would also make any fairness provision irrelevant as the state-wide 2PP % would be distorted by exhaution.

— Antony Green – elections (@AntonyGreenElec) July 1, 2020

ABC election analyst Antony Green told InDaily he had observed OPV at close quarters for decades in Queensland and New South Wales, where Labor introduced it in 1980 “and they’ve hated it ever since”.

“It prevents a three-cornered contest,” he said – an outcome that would have prevented the Liberals losing both Frome and the subsequent Fisher by-election in 2014.

But he said the change was instituted in NSW “before the Greens arrived”, since when “Labor’s had real trouble”.

“A lot of Greens voters don’t like the other parties [and] the rate of preferences going to Labor goes up and down depending what they think of the two other parties,” he said.

Retiring Greens MLC Mark Parnell yesterday suggested he would be unlikely to support the change in SA as it would entrench the two party duopoly, but Green suggested “OPV actually gives a power to minor parties”.

“Because under full preferential voting, the Labor Party can sort of ignore the Greens to some extent, because they are confident of their preferences,” he said.

“But if Labor’s on the nose with Greens voters, many of them will just not give preferences.”

He said OPV “always works in favour of the party with the highest first preference vote”.

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