A key independent MP already appears to be at odds with federal Labor, less than 24 hours after it secured his support for Australia's first minority government in 70 years.
Tony Windsor announced his decision to support Labor on Tuesday, giving the the party one of four crossbench votes it needed to form government.
However, the Gillard government's tenuous relationship with the country independent has hit a snag over Labor's proposed 30 per cent mining tax.
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Mr Windsor wants the minerals resource rent tax to be discussed at a tax summit next year, which was one of Labor's many offerings to win the independents over.
Treasurer Wayne Swan on Wednesday said the tax would not be on the summit's agenda because the government was in the process of designing the measure and preparing legislation for parliamentary approval.
"But I am involving all members of the parliament, including the independents, in the discussion," he told ABC Radio.
Mr Swan said Labor was committed to the tax, and a panel chaired by former BHP Billiton chairman Don Argus was looking at it in greater depth.
"Tony Windsor and the independents will have views about the design of that tax which they can express to the government but we have to move forward with legislation."
The opposition says the agreement which secured a Labor minority government had failed at the first hurdle.
"Labor is already sliding away from the deal they made with the country independents," opposition frontbencher Christopher Pyne told ABC Radio.
