Prime Minister Malcolm Turnbull won’t put his government’s election-triggering industrial relations bills before the Senate until he’s confident he has the numbers.
The government has left its bills to re-establish the Australian Building and Construction Commission and Registered Organisations Commission off next week's Senate agenda.
It comes as one of the legislation's strongest supporters, crossbencher Bob Day, resigned from the Senate this week.
Along with One Nation's Rod Culleton, he faces a High Court challenge over whether he was illegally elected, throwing two crucial crossbench seats in doubt for at least several weeks.
Manager of government business in the Senate Mitch Fifield on Thursday refused to say whether the bills - used to trigger the July 2 double-dissolution election - would be introduced before the end of the year.
Mr Turnbull confirmed the bills won't be put to the Senate until the government is confident it can get them passed.
"As John Howard always said, politics is governed by the iron law of arithmetic," he told reporters in Sydney.
"We will continue to talk to the crossbench and when we believe there is a majority there to support it, we will present the bills."
There are just three sitting weeks left on this year's parliamentary calendar and Mr Turnbull insists the legislation being put to the Senate next week is the most time sensitive.
It includes the same-sex marriage plebiscite bill, which needs to be passed soon if there is to be a national vote in February as planned.
Senator Culleton says he may postpone voting in parliament "in good will" until the question of whether he is eligible to be a senator is determined.
It means the coalition would need the support of eight out of nine crossbenchers to get its legislation passed.
Mr Turnbull laughed off suggestions the crossbench was in chaos, despite the multiple High Court challenges.
"There is no chaos," he said.
"This is orderly business, this is what happens in a constitutional democracy, governed by the rule of law."
Opposition Leader Bill Shorten says if there's no chaos, the prime minister needs to explain why he's holding off debate on the bills he used to trigger an eight-week election campaign.
"Mr Turnbull has been out and about laughing and saying there's no chaos to be seen here," he told reporters in Sydney.
"If there's no chaos at the heart of the Turnbull government, why are they not presenting their anti-worker, anti-union, anti-fairness industrial relations laws to be debated and voted on in the Senate?"