Likely new Labor leader Anthony Albanese says he "will consider" supporting the federal coalition's entire tax plan, after previously flagging support for the initial stages.
The opposition has indicated support for the first part of the plan geared toward low and middle-income earners, but not the government's aim to flatten the tax structure in 2022 and 2024 under the second and third stages of its plan.
But that could change if Mr Albanese is confirmed as leader, after nominations officially close on Friday.
"We will consider that, but let me tell you - it is a triumph of hope over experience and reality that the government knows what the economic circumstances are in 2025 or 2023," Mr Albanese told Nine's Today program.
"We'll give consideration to it, that's a matter for our proper processes."
If Labor resists the plan the coalition may have to consider splitting up its tax cuts, if it can't get them through the Senate without the opposition's support or the backing of crossbenchers.
Finance Minister Mathias Cormann has ruled this out.
"No, we will not split the bill. It is a holistic plan, it is a plan to provide income tax relief to all working Australians," he told Sky News.
"Labor should back our plan to provide income tax relief to all hardworking families around Australia. Obviously the Australian people endorsed that plan.
"It can't be taken apart, it can't be dealt with in bits and pieces, it will be put to the parliament as a whole."
Prime Minister Scott Morrison said it was clear Mr Albanese had not "learned the lessons of last Saturday" by opposing tax cuts that voters want.
"Bill Shorten did exactly the same thing - this is just Bill Shorten in a different shirt," Mr Morrison told reporters in Cloncurry on Friday.
Australian Associated Press