The federal government is a step closer to having its remaining budget measures passed after Family First Senator Steve Fielding announced a surprising backflip in view of the global financial crisis.
Senator Fielding on Monday said he would now support changes to the Medicare surcharge levy as well as a bill that will increase the tax imposed on pre-mixed alcohol drinks.
The support for the increase in the tax on alcopops is expected to add about $2 billion to the budget over the next four years.
Senator Fielding had previously voted with the opposition on both bills.
"We will support the government's remaining tax budget bills to bring about stability," Senator Fielding said.
"There are absolutely no caveats on it."
Senator Fielding said the ongoing turmoil in financial markets, and the threat posed to the Australian economy by the global economic crisis, meant it was important the government be allowed to pass all its budget measures.
"At this time of economic uncertainty and the massive downturn globally it is paramount that Australia's economic security is the focus of any decision making by the parliament."
Senator Fielding said he remained sceptical about whether the increase in the tax on alcopops would address the problem of binge drinking and had concerns about the effect on lower income earners of changes to the Medicare levy surcharge.
But he said the downward spiral in the economy made shoring up the nation's finances the priority for Australians.
"We've put the national interest first, as well as family first," he said.
"At the end of the day if the economy goes down the gurgler, then families are going to be severely worse off."
The government applauded Senator Fielding for his change in heart, while attacking the coalition over its continued opposition to the budget measures.
"I would urge the opposition to have a think about precisely where it is now positioned," Finance Minister Lindsay Tanner said.
"At this stage, the opposition is being given a lesson in economic responsibility by the Greens, by Senator Fielding and by (Independent) Senator (Nick) Xenophon."
Mr Tanner, who is acting treasurer while Wayne Swan is in New York for talks on the global financial crisis, called on the opposition to make good on its offer of bipartisanship in the face of uncertain economic times.
The opposition was "still seeking to tear down the budget surplus, the nation's insurance policy, the nation's buffer against the implications of the global financial crisis, in the Senate," he said.
"It is notable that not withstanding the renewal of the rhetoric about bipartisanship by the opposition yesterday, actions haven't changed."
However, the government still faces a hurdle in the Senate in terms of the changes to Medicare with Senator Xenophon saying he was not yet ready to declare support for the revised surcharge levy thresholds.
The Medicare bill in its original form would have raised the income thresholds at which the surcharge was applied for people without private health insurance from $50,000 to $100,000 for singles and from $100,000 to $150,000 for couples.
Last month, the government introduced a revised bill lowering the threshold for singles to $75,000.
Senator Xenophon said he would move an amendment to vary the thresholds to be at levels equivalent to them having been indexed to inflation since the tax's introduction in 1997.