He has also set out a bigger Commonwealth role in disaster preparedness, which is likely to include national standards on hazard reduction and related issues that could set him in conflict with the states.

In a speech to the national Press Club on Wednesday, Mr Morrison will say he is exploring the "constitutional and legal framework" that would allow an emergency declaration, making sure the Commonwealth had clear authorities to act without a state request, and to deploy Defence.

Mr Morrison faced criticism over the Commonwealth's slow and halting response to the bush fire crisis this summer. As late as January 2, he was insisting the response was a state responsibility. But by January 4, he had got the approval of the governor-general to send in Defence forces, including calling up 3000 reservists, without a state request.

Mr Morrison has since said the federal government had "pushed the constitutional authorities for us to act to its very edge".

In an ABC interview on January 12, he was asked whether he still needed state permission and responded, "We are acting under what I'd call a very agreeable environment".

Canberra lawyer and honorary associate professor at the Australian National University Michael Eburn pointed out in December that the Commonwealth has no overarching emergency management legislation and no power to declare a "national emergency", so a declaration would not trigger any extraordinary powers or authority to release funds and would at best be symbolic.

It would extend the power of the Commonwealth beyond what was provided for in the Constitution, he said.

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Mr Morrison's Wednesday speech is heavy with expectation that it will set his agenda for the year, but it will be delivered as he struggles to deal with the crisis engulfing Nationals deputy leader Bridget McKenzie over her handling of sports grants, and a police investigation still underway into how Energy Minister Angus Taylor came to distribute a false document in a failed attempt to discredit the Sydney mayor.

He has released an extract from his speech setting out plans for a greater federal role in disasters. While the Commonwealth role previously has been limited to responding to state requests, the bush fires have demonstrated the limits of that system, he will say.

States should remain responsible for police, fire, ambulance and medical services, but where the Commonwealth role should begin and end is less clear, he will say, setting out plans to explore that "legal interface".

He also wants a bigger national role in managing risks and preparing for disasters.

"This should include the setting of targets and transparent reporting on key actions, with enhanced national standards where necessary," his prepared speech says.

Mr Morrison is preparing to set up a Royal commission and he said one of its first tasks would be to audit what had been done with recommendations from previous disaster inquiries.

He pointed to more people living in fire-prone areas, increased fuel loads, local hazard reduction, access to aerial firefighting equipment, and the "consistency of disaster recovery arrangements or resilience in the face of a changing climate" as areas for investigation. He said Australia mist also learn from traditional Indigenous land practices.