The Federal Opposition is calling on the Government to immediately exempt emissions-intensive industries from the renewable energy target (RET) to secure jobs in those sectors.

The major parties are locked in a stand-off over lowering the target but agree on giving emissions-intensive trade-exposed industries (EITEs) like aluminium an exemption.

The Government has been under pressure from members of its own backbench to legislate the exemption before those industries are liable under the RET for another year.

Labor has advice from the Parliamentary Library that it could be done through regulation immediately and then tabled when Parliament resumes.

"The assistance rate for some or all EITEs could be changed to 100 per cent by amending regulation 22ZA," the advice states.

"The Renewable Energy (Electricity) Act would not necessarily need to be amended: the Renewable Energy (Electricity) Regulations could be amended to provide that exemption."

But the Parliamentary Library pointed to difficulties if trying to make a regulation retrospective.

Opposition Leader Bill Shorten is calling on the Government to act on the advice.

"The Government has been holding aluminium and other emissions-intensive companies to ransom, despite the fact both the Opposition and the Government support an exemption," he said.

"Either this Government doesn't care about protecting these jobs, or it is so incompetent that it's failed to examine how the exemptions actually operate."

The Australian Aluminium Council said it would be forced to pay between $50 million and $80 million if the relevant legislation was not passed by the end of March.

Unions fear jobs will go in the aluminium sector if a deal on the RET is not reached soon.

The target is for 20 per cent of Australia's energy mix to come from renewable sources such as wind and solar by 2020.

The current target was legislated at 41,000 gigawatt hours which, with demand for power falling, was likely to represent more than 20 per cent of Australia's energy mix by 2020.

Labor wants a gigawatt hours figure in the mid-to-high 30,000s and says there will be no deal if the Government does not lift its offer.

Federal Industry Minister Ian Macfarlane told the ABC last week he was not considering anything above 32,000 gigawatt hours.