Prime Minister Kevin Rudd is maintaining pressure on the opposition, reiterating his claim coalition senators are mounting a $6 billion raid on Labor's first budget.
Already, the Senate has knocked back three budget measures - the $555 million luxury car tax increase, a $23 million contribution from drug companies to the cost of the Pharmaceutical Benefits Scheme (PBS), and closing a million-dollar tax loophole for family trusts.
Under threat are the government's plans to increase the income thresholds at which the Medicare surcharge levy applies to taxpayers without private health insurance, a tax hike on alcopops, and scrapping an excise exemption on condensate, a light crude oil developed from natural gas.
Mr Rudd says the coalition's position is wrong, especially during a time of global economic uncertainty.
"The cornerstone of responsible economic management is to have a strong surplus," he told the Seven Network today.
"We brought one down in the (May) budget - $22 billion - because we need that as a buffer for the future.
"Now the Liberals are conducting a $6 billion raid on it and it is a real problem."
If the opposition was successful it would put upward pressure on inflation and interest rates, Mr Rudd said.
"Having just got the first interest rate cut in seven years, that is just exactly the wrong way for the Liberals to go."
Mr Rudd says the surplus must be directed into long-term productive investments.
"This has been the sustained advice in multiple warnings by the Reserve Bank of Australia," he told ABC Radio.
The revenue generated by the luxury car tax could be directed towards public transport.
"It's $555 million which the Liberal Party has chosen to preserve for the purposes of those ... buying luxury cars as opposed to that half billion dollars going into our infrastructure investment fund for the future, which, subject to views of Infrastructure Australia, could be directed towards public transport.
"So, it's half a billion dollars for Porsches, as opposed to half a billion dollars for public transport."
Mr Rudd said five of the leading industrial economies had experienced negative or zero growth in the June quarter and it was tough going in the global economy.
"But we believe we have a clear strategy to steer Australia though this and that means ensuring that we preserve our budget surplus that provides us with a buffer for the future," he told Sky News.
"We think on the basis of a strong budget surplus, a commitment to productive investment through our nation building strategy, that we can steer Australia through."
Mr Rudd said he believed the opposition had embarked on a consistent strategy since the start of the year to talk down the economy.
"That's just grossly irresponsible," he said.