Federal Treasurer Wayne Swan says claims by a senior Liberal that a coalition government would have kept the federal budget in surplus during the global financial crisis (GFC) are "delusional".
Opposition frontbencher Christopher Pyne believes the coalition would have kept the budget in the black over the past five years.
"I think most people accept that we would have had continuing surpluses," he told Sky News on Monday.
"We would have had money in the bank."
But Mr Swan said the shadow education minister was pretending the 2008-2009 GFC never happened.
"These people are delusional," Mr Swan told reporters in Brisbane.
He said while falling commodity prices would make it more challenging for the government to achieve a budget surplus, it was the right thing to do.
Mr Swan declined to concede the budget could remain in deficit.
"I don't deal with hypothetical situations," he said.
Mr Swan also had no intention of adjusting his budget forecasts in the near term.
"We don't redo our budgets every month when new data comes out," he said.
"We have a look at what's going on but where you've got an economy with low unemployment, growth around trend, strong investment pipeline, then it's appropriate we return to surplus."
However, Opposition Leader Tony Abbott claimed the government wouldn't be able to return a surplus because it was wasting money transporting asylum seeker boat arrivals.
"Currently the government is spending more money flying illegal boat arrivals around the country than it is subsidising the Royal Flying Doctor Service," he told reporters in Sydney.
Mr Abbott also claimed every boat that arrived in Australian waters cost taxpayers $13 million.
"That is the sorry pass we have come to in this country because we have a government that is incompetent and untrustworthy," he said.
Business Council of Australia chairman Tony Shepherd has called on Labor to spell out a "clear plan" to deliver a surplus in 2012/13, rather than base its claims on optimistic Treasury forecasting.
Mr Abbott said the government was "crab walking away" from its commitment to deliver surpluses.
"A coalition government gets the budget into surplus, it pays down debt, it produces assets," he said.
"That is the kind of good economic management which provides the kind of social dividend which Australia came to enjoy under the Howard government."