The government faces the seemingly impossible task of convincing enough Senate crossbenchers to support slashing the tax rate for all businesses from 30 to 25 per cent.

Ahead of the cuts being debated and voted on in the upper house next week, senior ministers have publicly rebuffed all offers of compromise.

A suggestion from independent senator Derryn Hinch to limit the tax relief to companies with turnovers of up to $500 million and exclude the big banks has been consistently rejected.

Mr Morrison said the legislation would be put up for debate as it stands but acknowledged he and others had been locked in discussions with crossbench senators for some time.

"They've continued over the course of this week, prior to that bill being considered next week and we'll see what happens there," he said on Thursday.

"I'll leave those discussions and what's been put about in those negotiations in that room and that will present itself to the Senate at the appropriate time."

On current numbers the legislation appears doomed to fail, with just four of 10 crossbenchers backing the cuts, leaving the government four votes short.

Asked to guarantee the government would take the tax cuts to the next election if the vote fails, Mr Morrison said: "I can guarantee that we're putting it into the Senate ... and we're going to seek to pass our full promise that we made at the last election."

One Nation leader Pauline Hanson, who holds two crucial Senate votes, said she had not changed her position on the company tax cuts.

"I said to the government you start reining in the multinationals ... before I say turn around and give them any more tax cuts," she said on Thursday.

She said the government had indicated to her it was not interested in the $500 million threshold.

Australian Associated Press