As revealed by The Australian Financial Review on Tuesday, the government was still trying to convince Senator Xenophon to agree to a tax cut for companies with an annual turnover up to $50 million.

This $50 million turnover had the support of most of the rest of the crossbench, including the four One Nation senators and Derryn Hinch who said it would be good for medium-size businesses in his native Victoria.

But in a late twist on Thursday, it emerged One Nation was fixed on $50 million and would not go lower. This means that if Senator Xenophon refused to go above $10 million, and One Nation refused to go below $50 million, there would be no deal at all. The NXT was not ruling out agreeing to the second phase of the 10-year plan which would give a 27.5 per cent rate to companies with turnovers up to $25 million.

Much of Thursday night was spent debating changes to 18C of the Racial Discrimination Act. The substantive changes to the wording of the act, as pushed by the government, were doomed to fail, but the Senate passed non-controversial changes to process.

Confident of deal

Senator Xenophon has refused to budge over $10 million unless the government could fix the energy crisis in his home state of SA.

Senator Xenophon believes that despite goodwill from the government and numerous announcements in recent weeks to secure a domestic gas and electricity supply, none of this would be delivering concrete results in time for the Senate vote.

If the government secures the passage of some of the package, either with a $10 million or $50 million turnover, it is not ruling out trying again to legislate its full company tax cut plan before the next election.

Prime Minister Malcolm Turnbull, who on Friday last week all but confirmed the government would keep the remainder of the $48 billion tax package in the May budget after the Senate vote, indicated again that the government would continue to fight for the package in its entirety.

"Company tax is not just a tax on businesses, it is a tax on jobs, a tax on workers and a tax on workers' pay packets," he told the The Australian Financial Review on Thursday.

Mr Morrison, refused repeatedly to say whether the remainder of the plan would be in the budget.