Mr Turnbull yesterday declined to tie himself into detailed undertakings on the deficit and debt but adapted a line that the Howard government regularly used on interest rates, when it said they would always be lower under the Coalition.

The Government predicts a return to surplus by 2015-16.

But Mr Turnbull told the National Press Club that Labor had "no hope" of ever presiding over a surplus budget because it had no discipline.

The familiar pattern was that after Labor, "the Coalition comes back and we fix it up".

After the Coalition had paid off Labor's debt and left $45 billion in the bank, Mr Rudd was "dealt the best hand of economic cards any prime minister could ever seek.

"Now we're promised seven or more years of huge budget deficits.

"Sounds like an even more frightening version of the Pharaoh's dream …

"We've had seven months of economic conservatism or prosperity, followed by at least seven years of austerity and deficits.

"And what will the debt be at the end of it? A deficit of $300 billion frankly looks optimistic."

Pressed on what debt would be under his policies, Mr Turnbull did not give a figure. Labor claims he has already embraced $177 billion of debt, but Mr Turnbull denies this.

Prime Minister Kevin Rudd said Australia's net debt would be the lowest of any major advanced economy for the next decade.

Finance Minister Lindsay Tanner stressed the budget needed to be brought back to surplus "as quickly as possible" and Tuesday would be "the first instalment" of the necessary tough decisions.

"It is vital that we don't allow these deficits to continue indefinitely … We don't have to do all the work in one budget but we've got to make a very important start."

Maintaining Australia's triple-A credit rating was a very important objective for the Government, Mr Tanner said.

The rating affected the cost to the budget of the borrowing the Government had to undertake.

"We are already projecting a cost of $2-3 billion a year in three or four years time, and that's likely to be higher just from the borrowing that we need to do to cover the huge loss of revenue off the back of the global recession.

"We don't want to see that go any higher than it has to, and we certainly don't want to see that increase because of a downgrading of Australia's rating," Mr Tanner said.