Nick Xenophon has vowed to "keep the bastards accountable" on energy costs, warning a future a South Australian minority government will lose his support if it can't cut power prices by 20 per cent within two years.
The benchmark is included in SA-BEST's energy policy, released on Thursday, which will also push for a non-profit energy retailer to provide cheaper power to lower-income households and small businesses.
The price cut demand hinges on SA-BEST holding the balance of power after the March 17 poll.
"We just want to keep the bastards accountable on energy prices, whoever those bastards may be," Mr Xenophon told reporters.
"I think there is nothing like the prospect of a government losing its position to focus their minds on the issue of energy."
SA-BEST's scheme for a non-profit retailer would be available to households with an income up to $75,000 and to businesses with power bills under $20,000.
To be known as the Community Electricity Trust of SA, the retailer would also enter into a tender process to develop a new 150-megawatt power station.
The party says 50,000 households and 5000 businesses would be able to access cheaper power through the program and could expect price cuts of about 20 per cent.
South Australian Premier Jay Weatherill was reluctant to weigh in on SA-BEST's plan, telling reporters he wanted more details.
However, Opposition Leader Steven Marshall said Mr Xenophon was "signing up with Labor".
"Today he is essentially setting up a shopfront to sell Jay Weatherill's hideously expensive electricity in South Australia," he said.
But consumer group Solar Citizens welcomed Mr Xenophon's commitments to help people on low incomes and small businesses.
"South Australians have been ripped off by big power companies for too long," campaigner Dan Spencer said.
"Nick Xenophon and The Greens have now committed to establishing a government-backed, non-profit retailer and we hope to see Labor and Liberals back this idea as well."
Australian Associated Press
