Opposition Leader Tony Abbott says a report by an independent forecaster shows the federal Labor government will never deliver a budget surplus.
The Deloitte Access Economics report, released on Monday, warns that the government's projected $1.1 billion surplus for the 2012/13 financial year is more likely to turn into a $4 billion deficit.
"The government is never, ever going to deliver even a dishonest surplus, let along the honest surplus the Australian public deserve," Mr Abbott told reporters in Canberra.
This was despite that on at least 150 separate occasions Treasurer Wayne Swan and Prime Minister Julia Gillard had promised a surplus, "no ifs, no buts", the opposition leader said.
"These people have got to deliver on their commitments," he said.
"If they break their solemn promise they should be criticised and they should be judged by us and by the electorate."
Mr Abbott reaffirmed a pledge to deliver a surplus in the first three budgets of a coalition government.
The coalition would boost productivity and reign in government spending, over time allowing it to make sustainable cuts to government expenditure and taxes.
"Of course things take time, but we will do better than this government from day one," he said.
Mr Abbott added the coalition had no plans to alter the application of the 10 per cent GST.
"We have no plans to change, and I don't believe the government has either," he said.
"We certainly think that the existing system is the system we should stick with."
Shadow treasurer Joe Hockey said the government was continuing to "crab walk" away from a budget surplus in the wake of poor job ads numbers released on Monday.
"The most disappointing aspect of the last few days is the fact that the government is continuing to crab walk away from its promise of a budget surplus," he told reporters in Sydney.
"Of course commentators are now revealing the truth about the budget because Wayne Swan won't.
"The government cannot keep a promise, it has no economic strategy, it has no fiscal strategy and it has no taxation strategy."