Malcolm Turnbull is refusing to say whether he will abandon big business tax cuts if they are rejected by the Senate.
Hours after the prime minister sensationally shelved plans to implement climate change targets, the opposition asked whether his signature corporate tax plans would suffer the same fate.
Mr Turnbull quickly decided the best form of defence was attack, but studiously avoided answering the question.
"The Labor Party stands for higher personal income taxes, higher business and company taxes, opposing multinational tax avoidance," he told parliament on Monday.
"The reality is the Labor Party does not have one policy that will encourage one business to invest $1 or hire one employee."
Debate is continuing in the Senate on the draft laws slashing the tax rate for all businesses from 30 to 25 per cent.
The cuts are unlikely to pass as both Labor and the Greens oppose them, and just four crossbenchers are backing the cuts, leaving the government four votes short.
Australian Chamber of Commerce and Industry chief executive James Pearson says the tax cuts are being held hostage to short-term political opportunism.
"Politics is getting in front of good policy," Mr Pearson told reporters.
"Australia, frankly, can't afford not to extend the business tax cuts to all sizes of businesses."
The legislation is set for a vote on Tuesday after debate raged late into Monday night.
Former deputy prime minister Barnaby Joyce concedes the big business tax cuts are a hard sell, but insists they are critical for Australian companies competing in an international market.
"We've got to clearly explain to people, you might think they are big bastards, but they are big bastards who might pack up here and go somewhere else," Mr Joyce told Sky News.
Queensland Labor senator Murray Watt can't see any prospect of the tax changes passing.
"If any party, whether they be Liberal, One Nation, or Labor, backs in these tax cuts, they've got a death wish," he told reporters in Canberra on Monday.
"Australians are firmly against these tax cuts."
Senior Turnbull government minister Dan Tehan concedes that "decisions will need to be made" if the Senate blocks the cuts.
"We just have to wait and see what the Senate does today and then obviously we'll have to make decisions after that," he told ABC radio on Monday.
