Victorian Premier Daniel Andrews is expected to offer taxpayer-funded support to save the struggling Portland aluminium smelter within weeks, as federal counterparts vowed to ensure all big industrials were appropriately rewarded for the surge capacity they offer the National Electricity Market.

The four-year, $200 million lifeline Mr Andrews' government provided to Portland in 2017 will expire in less than seven months and a spokeswoman for the state said talks over an extension of that package had been "constructive".