Australian Greens leader Bob Brown believes the market should decide the fate of Victoria's Alcoa plant.
Alcoa said this week it would review the viability of its Point Henry aluminium smelter because higher metal prices, input costs and exchange rates had made the plant unprofitable, raising the prospect of job cuts.
Senator Brown said on Thursday market forces should decide the smelter's fate.
"Here you are talking to a Green who defends the market, while the big parties defend public subsidies," Senator Brown told reporters in Canberra.
"It's obviously difficult and we are concerned about jobs, but this is an industry which I don't think has been investing wisely and the market does come into play, as indeed it is doing with the logging industry in Tasmania at the moment."
The plant employs 600 people, who will have to wait until the end of June to find out whether they will keep their jobs.
Its operations, which emit about 1.6 million tonnes of carbon every year, have been bolstered by state electricity subsidies and it will receive 94.5 per cent of its carbon permits for nothing under the carbon pricing scheme to start on July 1.
Senator Brown began his political career four decades ago campaigning against the flooding of Tasmania's Lake Pedder area to build a hydro-electric power station, which was to provide power to an Alcoa plant.