Greens leader Christine Milne urged Labor not to ''run up the white flag'' when it came to scrapping the carbon tax. She also said Labor should stop thinking about itself and instead ''think about the children'' when it came to formulating a position on the tax.

As Fairfax Media reported on Tuesday, Labor was expected to support axing the carbon tax, with senior figures now convinced that the case for action on climate change would be sold more easily if the politically toxic tax was scrapped.

''Labor is positioning itself to backflip and cave in once again on actually addressing global warming,'' Senator Milne told reporters in Hobart on Tuesday.

''So many people around Australia will be disappointed beyond belief.''

Senator Milne said that climate change was the ''greatest challenge we face''.

''I call on the Labor party. Stop just thinking about Labor and the power that Labor might have,'' she said.

''Think about the planet. Think about the children, the next generation.''

Labor's policy going into the election was to scrap the carbon tax and introduce an emissions trading scheme a year earlier than planned. However, since losing the September 7 poll, Labor has been wrestling with what to do about the Coalition's plan to repeal of tax, with some saying it must hold the line to show voters and demoralised supporters that it still stands for something.

But party leaders have been considering what the party should put to voters in the lead-up to the next federal election.

They argue that Labor proposed to ''terminate'' the tax at the last election. Party advocates for a repeal of the carbon tax said to simply block the move would allow the government to continue to punish it politically.

The Coalition say its strong election win gives it a mandate to repeal carbon pricing and introduce its direct action climate change policy. Under the Coalition's policy, taxpayer dollars are used to pay polluters to reduce emissions and fund other initiatives in forestry, carbon capture and recycling.

On Tuesday, a spokesman for Labor leader Bill Shorten said the party believed climate change was real and needed "strong and sensible action".

''We indicated clearly at the election our intention to terminate the carbon tax and move quickly to an emissions trading scheme . . . the same policy John Howard took to the 2007 election,'' he said in a statement.

The spokesman attacked the Coalition's direct action plan, arguing it would take Australia backwards.

''What we will not support is a policy that sets no limit on carbon pollution, but costs business and households more. It's no wonder that experts are united in their view that the Coalition's direct action policy will take Australia backwards – it will cost more but it will be less effective,'' the spokesman said.

On Tuesday, West Australian Labor senator Louise Pratt acknowledged that there were discussions going on within the party on the carbon tax question.

''I've been part of some discussions about these issues,'' Senator Pratt told Fairfax Media's Breaking Politics program, but would not speculate on the final outcome – noting that the question had to be put to caucus and the shadow cabinet.

Senator Pratt also said that it was now the Coalition's responsibility to come up with ''meaningful action'' on climate change.

''We're no longer the government. The onus really needs to be on the Coalition and their direct action policy has massive holes in it,'' she said.

Shadow assistant treasurer Andrew Leigh said Labor would support scrapping the carbon tax – as per the policy Labor took to the 2013 election – but insisted the tax needed to be replaced with an emissions trading scheme.

''We said we would scrap the carbon tax, the fixed price period, and move straight to a floating emissions trading scheme,'' Dr Leigh told Sky News on Tuesday.

''That's something that we will be happy to vote for on the floor of parliament.''

While speculation mounted about Mr Shorten supporting the repeal of the carbon tax, Labor backbencher Graham Perrett took to Twitter, quoting the author of To Kill a Mockingbird, Harper Lee: "Real courage . . . Is when you know you're licked before you begin but you begin anyway and you see it through no matter what."

Mr Perrett followed with a quote by the American songwriter John Mellencamp: "You've got to stand for something, [sic] Or you're gonna fall for anything."

He has been a strong and consistent advocate of the price on carbon, telling his constituents that "a carbon price is not a tax on households''.

Asked on Tuesday, whether his tweets had anything to do with Labor's internal struggle over the carbon tax, Mr Perrett told Fairfax Media he would "leave that [speculation] to the commentators".

"I'll keep my powder dry for the moment," he said.

Shadow climate minister Mark Butler said Labor was "still working through" the Abbott's government's carbon repeal legislation and he would not comment on how the opposition would deal with it tactically.

"The fundamental problem with Tony Abbott's legislation is, not that it terminates the carbon tax... but that it throws the baby out with the bathwater," Mr Butler told ABC TV on Tuesday.

"It gets rid of the idea... of there being a legal limit on carbon pollution. This is an utterly critical element," Mr Butler said, "and we're simply not going to support that."

"Although we support the termination of the carbon tax we insist that there must be a legal limit on carbon pollution and there must be a proper mechanism to get to that point."

Parliamentary secretary for environment Simon Birmingham said he wasn't convinced Labor had heeded the electorate's message that ''they want to see the carbon tax gone – gone in its entirety, not just gone for a year''.

''We will be introducing legislation to parliament that repeals the carbon tax in its entirety from 1 July next year forever more,'' he said.

With Tom Allard, Mark Kenny, AAP and Jonathan Swan