The coalition will stick with tax cuts for big companies even if the Senate rejects them, as Labor targets Malcolm Turnbull's wealth in new attack ads.
Senators are due to vote this week on whether to give corporations a tax cut, but the coalition says it won't drop the plan even if it gets rejected.
"That's the policy we're taking to the next election," Deputy Prime Minister Michael McCormack told ABC radio on Monday.
The government wants the upper house to reduce the corporate tax rate to 25 per cent - so far it has only secured a cut for businesses with a turnover of up to $50 million.
A lack of public and upper house support led to suggestions the coalition will drop the policy, but Mr McCormack insisted it is staying.
A new poll shows Mr Turnbull is still ahead of Bill Shorten as preferred prime minister, even though Labor leads the two-party preferred vote.
Monday's Fairfax/Ipsos poll pegged Mr Turnbull at 51 per cent against 33 per cent for the Labor opposition leader.
But the coalition continues to lag behind Labor on a two-party preferred basis, at 47-53 per cent.
The opposition has ramped up attacks on Mr Turnbull, releasing negative ads highlighting his wealth and his indirect financial interest in 32 big corporations.
"He always sides with the millionaires and the multinationals over middle Australia," Labor's finance spokesman Jim Chalmers told ABC radio on Monday.
The prime minister wasn't having it.
"They want to attack me having a quid," he told reporters in Canberra.
"They want to attack me and Lucy for working hard, investing, having a go, making money, paying plenty of tax, giving back to the community."
Mr Turnbull also stuck by the proposed company tax cuts, which need support from Pauline Hanson's One Nation.
Senator Hanson wants the government to bring in more tax from multinational corporations, which Mr Turnbull said it was already doing.
"We've been relentless on this," the prime minister told reporters in Canberra.
"We're very committed to everyone paying their fair share of tax."
Treasurer Scott Morrison said Australia had been the toughest country in the world on multinational tax avoidance, and he was looking at ways to do more.
