InDaily revealed last week Chapley would nominate to stand for the crucial seat of Adelaide, with the blessing of Premier Jay Weatherill.

However, it has now emerged Chapley has walked out on Weatherill’s left faction, joining the party’s right-wing Labor Unity group in order to contest Adelaide – a move that insiders say is causing significant angst within the Left.

Chapley today confirmed she had joined the Right, telling InDaily: “We have a common aim of staying in government and maintaining economic and social momentum in this state.”

Sources have told InDaily her defection is a significant blow to Labor’s PLUS [Progressive Left Union and Sub-Branches] faction, having now lost one of its brightest prospective hopes before she even reaches parliament.

It’s understood Chapley walked out after a standoff over where she should run. InDaily has been told the faction’s powerbrokers were only prepared to put her up in the northern suburbs seat of King – effectively a new seat and the party’s most marginal one under the proposed new boundaries.

But insiders argue a “progressive” left-winger like Chapley would have been a poor choice for a mortgage-belt northern suburbs seat, and it’s understood she was not keen to nominate there.

She previously stood against Liberal leader Steven Marshall in the inner-eastern suburbs seat of Dunstan at the 2014 state election, cutting his margin to just 3.1 per cent after a well-resourced campaign.

Chapley is the in-house lawyer for her family business, the Chapley Group, which owns a Foodland supermarket chain.

The PLUS faction, convened by United Voice official David Gray, has been an unhappy camp in recent weeks, with insiders telling InDaily there was broad dissatisfaction that the leadership had failed to consult with members and had kowtowed to the superior numbers of Labor Unity in various preselection deals.

“Basically, the Left are always seen as either giving up a seat or getting the rough end of the pineapple on every deal,” said one insider.

Recent machinations have seen the Left give up the key seats of Badcoe and Florey, while picking up an extra guaranteed seat in the Upper House and King, with a nominal 1.4 per cent margin.

A clutch of Industrial Left unions last week openly challenged the trade-off to install Australian Workers Union official Justin Hanson in the Legislative Council while ceding Frances Bedford’s Florey to arch-conservative Jack Snelling.

Insiders say while the challenge to Hanson was soundly defeated – 128 votes to a combined 29 – it still represented a decisive split in the left, if the 80-odd right-faction votes are discounted.

High-profile left-winger Gail Gago – who will retire at the 2018 election – said she believed Chapley “will make a fabulous candidate for Adelaide and I think she’s got a very good chance of winning it”.

However, she refused to be drawn on Chapley’s defection or the Left’s ongoing division, saying: “I’m obviously not going to discuss factional issues – they’re a matter for internal consideration.”

While Adelaide remains a nominal Liberal seat with a 2 per cent buffer, it’s a seat the ALP knows it must win to retain Government, with the likely loss of seats such as Elder and Colton under the redrawn boundaries.

Interestingly, parliament’s most senior left-winger is Weatherill, who last week claimed a personal influence in Chapley’s nomination.

“I’ve asked Jo to consider her candidature for the seat of Adelaide for the next state election,” he said in a statement at the time.

“Jo has a real passion for representing people and I’m sure she’ll make it her priority to meet as many people in the seat of Adelaide as she possibly can.”

InDaily has sought comment from David Gray, who is currently in meetings in Canberra.