A plan to raise more money by taxing big offshore gas and oil companies faces an uphill battle as independent senator David Pocock and the Greens confirm they will vote against the proposal as it stands.
Senator Pocock said proposed changes to the petroleum resource rent tax was a "disappointing" and "weak" approach from the Albanese government and called for it to be higher.
"I would much rather see the rate of PRRT raised from 40 per cent up to 50 or 60 per cent, which is what a bunch of experts are saying should happen," he said on Wednesday.
"We've got to actually look at getting a fair return for our resources (because) these gas companies are making record, wartime profits selling our gas back to us at international prices and they're not even paying the PRRT."
Without changes from the government, Senator Pocock said he would vote down the proposal.
"I can't cop them telling Australians who are doing it tough that 'I'm sorry, the budget is tight'," he said.
"Then, when Treasury gives them options to actually bring in more money over time, they go for the option that isn't going to raise more money. It's simply going to bring a bit more money in earlier."
The government won't need crossbench support if the coalition backs the bill, which has yet to be published or introduced to parliament.
The Greens, two Jacqui Lambie Network senators and Senator Pocock would support the tax reform if the government agreed to lower the deductions cap.
The bill proposes to cap tax offsets at 90 per cent of assessable income but the crossbench want this dropped to 80 per cent to secure their votes.
Lowering the cap would mean at least 20 per cent of a gas company's revenue is subject to the tax.
It would raise an additional $2.6 billion over four years while the government's existing proposal would reap $2.4 billion.
Greens senator Nick McKim said the ball was in the government's court.
"The choice is clear, either double the revenue by working with the Greens or halve the revenue by working to the satisfaction of (Opposition Leader Peter) Dutton and the gas corporations," he told reporters in Canberra.
"We hope they make the right choice, it really is an absolute no-brainer."
