Opposition Leader Bill Shorten is set to lock in Labor to retain the coalition's budget repair levy on the rich when he delivers his budget reply speech.
Mr Shorten is due to give his budget reply speech on Thursday evening at Parliament House.
Treasurer Scott Morrison's second budget delivered on Tuesday signalled an end to the two per cent levy imposed on those with a taxable income over $180,000 a year, which was temporarily put in place in 2014 to help balance the books.
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But Labor believes that with the deficit for 2017/18 being 10 times worse than the Liberals' first budget predicted, now is not the time to remove the levy.
The opposition is still weighing up whether to back a hike in the Medicare levy on most Australian taxpayers to fund disability insurance, which could also be confirmed on Thursday.
The government wants to increase the Medicare levy paid by almost all workers by half a percentage point to 2.5 per cent of taxable income from July 1, 2019, to provide long-term funding for the NDIS.
"At a time when the government is asking every other working Australian to pay a higher rate of tax, Labor will not support spending at least $1.2 billion each year on the wealthiest two per cent," Mr Shorten will tell parliament.
"It is not fair that - under this government - someone on $1 million will be over $16,000 better off ever year while Australians on $30,000 and $40,000 will have to pay more."
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The opposition leader will emphasise budgets are about "choices".
"(Mr Turnbull's) chosen his own political survival over everything else."
With many commentators describing the 2017 budget as "Labor lite", Mr Shorten will describe it as "Liberal through and through".
Prime Minister Malcolm Turnbull, Treasurer Scott Morrison and other ministers will continue their media blitz selling the budget.
They're facing a backlash from the bankers over the surprise $6.2 billion levy on Australia's largest financial institutions.
Chief executives of Commonwealth Bank, National Australia Bank, ANZ and Westpac all labelled Mr Morrison's levy a "bank tax", with three of the four explicitly saying the cost will be passed on.
Former prime minister John Howard also called it a tax.
Finance Minister Mathias Cormann said he wouldn't be drawn into a debate on "semantics".
"It is designed in a way to ensure that the banks do not have to pass it on to their customers, it specifically excludes from its base day-to-day bank accounts and day-to-day mortgage accounts," Senator Cormann told ABC Radio on Wednesday night.
Treasury officials will brief bankers in Sydney on Thursday.
