An unexpected decision by Nationals MP Kim O’Keeffe to vacate her seat of Shepparton before the November election has abruptly transformed the Goulburn Valley electorate into one of the state’s most fascinating political contests.

It is a race thus far without a declared candidate for any of the three parties in the hunt for the seat – the Nationals, the Liberal Party and One Nation – and all have their eyes on the same potential recruit, City of Shepparton Mayor Shane Sali.

Nationals leader Danny O’Brien said the loss of O’Keeffe, herself a former local mayor who in 2022 regained Shepparton from two-term independent Suzanna Sheed, would make more challenging his party’s already difficult job to defend the seat.

It leaves the Nationals having to cover for retiring members in three of their nine lower house seats – Shepparton, Murray Plains and Gippsland East — and without the benefit of incumbency in trying to hold back the orange tide in electorates vulnerable to Pauline Hanson’s populism.

Murray Plains, Shepparton and Benambra – a Liberal-held seat where long-serving MP Bill Tilley is retiring due to ill health – all look across the Murray River to the NSW federal electorate of Farrer where, just two months ago, One Nation wiped out the Coalition partners in a by-election mauling.

“It is always a bit harder when you have got a retiring member and trying to transition a seat, but we are confident we will get a strong, local champion again, like we did with Kim, and fight hard to win every vote,” O’Brien said.

“We don’t shy away from the fact there will be a strong contest. There always is. There is no such thing as a safe seat anymore and that has probably been the case for the Nats for longer than anyone else.”

O’Keeffe campaigned in Shepparton with O’Brien and Opposition Leader Jess Wilson just two weeks ago but then announced she would not recontest her seat. “The time has come for me to slow down, spend more time with my family, and some much-needed self-care,” she said in a statement posted on her website this week.

O’Keeffe declined to expand on her reasons when contacted by this masthead.

The success of the Nationals in winning back regional seats from independents in Shepparton, Mildura and Morwell at the last state election, when added to the personal electoral brand of some of their longer serving MPs, is a potential bulwark against One Nation in Victoria.

Redbridge director Kos Samaras, whose polling company has done seat-by-seat modelling for the state election for the Victorian Trades Hall Council, is cautious when projecting losses from the Nationals to One Nation.

“One Nation needs an extraordinarily high primary vote to win,” Samaras said. “Against an incumbent, popular, National Party MP, that is going to be very difficult. Where a seat is vacant is where you will see One Nation take its gains.”

The exception to this rule, Samaras says, is the Latrobe Valley seat of Morwell, which he describes as “ground zero” for One Nation in Victoria.

In Shepparton, the most pressing question is the political future of Sali, a councillor known locally as the “handsome mayor” and familiar to Today Show audiences. He is mooted as a potential candidate for the Nationals but his family, one of the region’s celebrated migrant stories, has strong links to the Liberals.

One Nation is understood to have Sali on their wish-list of candidates but his fellow councillor, Steve Threlfall, a well known local shooting and sporting goods store owner, confirmed on Thursday he was also interested in representing Hanson’s party. “I’m certainly chasing pre-selection,” Threlfall said.

One Nation’s sole representative in the Victorian parliament, upper house MP Rikkie-Lee Tyrrell, has her electorate office in Shepparton.

Sali, when contacted by this masthead, paid tribute to O’Keeffe’s contribution to the region as a state MP and local councillor but declined to canvass his political options.

“I’m the current Mayor, I’m not a member of any political party and my focus has always been the outcomes that our community is trying to achieve,” he said.

He added that, irrespective of who next represents Shepparton, there is broad consensus about what the regional centre needs – better roads, more frequent train services, an expanded sports and events centre, and a second crossing over the Goulburn River to stop heavy trucks from rumbling along the existing causeway through the centre of Mooroopna and Shepparton.

Shepparton is Victoria’s only major regional centre without an integrated cancer centre at its local hospital.

The closure of the Bega Cheese factory at the end of last month – with the loss of more than 300 jobs – crystallised regional insecurities about the combined impact of water buy-backs under the revised Murray Darling Basin Plan and rising gas prices on agriculture, horticulture and food manufacturing.

Linda Nieuwenhuizen, the chief executive of the Committee for Greater Shepparton, said the recent political history of the region suggested voters were less guided by party loyalty than a yearning for practical outcomes.

“We want to see the next government have a real ambition for what regions like ours can deliver,” she said. “We are a big food manufacturing and production centre. We know there is global growth happening that we want to be a part of.”

Sheed, who represented Shepparton between 2014 and 2022 and is not planning to run again, said there was a lot of hype about One Nation and a level of voter frustration she didn’t encounter when she entered state politics.

“It feels angrier now than then,” she said. “The major parties need to accept that One Nation’s rise is not just an electoral challenge or a political problem. It’s the result of historic and ongoing policy failings. The remedy, therefore, must be better policy”.