Prime Minister Julia Gillard has soften her tone and argued with new semantics to push for the carbon tax.

She said in a press conference in Melbourne on Friday that the carbon tax will only be temporary and replaced by an emissions trading scheme.

"This isn't about the terminology," Ms Gillard told reporters in Melbourne.

"(But) whatever you want to call it a carbon tax is temporary (while) an emissions trading scheme is permanent."

Ms Gillard insisted that it was only Opposition leader Tony Abbott who calls the initial fixed price period a carbon tax.

She said it has to be emphasized that the carbon tax is to be set on the initial phase and will slowly veer to a more permanent emissions trading scheme.

"People listening to Mr Abbott over recent months may have got the impression that the carbon tax was going to be permanent.

But it's believed Labor has guaranteed the transition to an ETS will occur in mid-2015.

The multi-party climate change committee is expected to announce within weeks the carbon price per tonne of pollution and associated compensation for households and business.

But Ms Gillard said the deal wasn't done yet.

"We're still working hard to finalise all details of the scheme before we announce them all publicly."

Industry Campaign: Anti-Carbon Tax

Meantime, an alliance of industry groups has indicated it's prepared to spend $10 million on an advertising campaign to "build public opposition to the carbon tax so that it is either substantially modified or fails to pass the parliament".

The campaign reportedly will include television, radio, print and internet ads and start within seven days of the government announcing the final design of the scheme.

The Australian Trade and Industry Alliance is made up of organisations including the Australian Chamber of Commerce and Industry, the Minerals Council of Australia and the Australian Coal Association.

Retailers also have backed the campaign.

"Retail trade figures have been in the doldrums in most states for more than a year now and higher prices resulting from a carbon tax will further harm the sector as it battles with the rapidly growing on-line shopping market," National Retail Association executive director Gary Black said in a statement. With reports from the Sydney Morning Herald