Immigration Minister Peter Dutton could be given a greater role in coordinating counter-terrorism policy among changes to national security which include military intervention in terror incidents.
Federal cabinet on Tuesday is expected to discuss an overhaul of national security coordination following a review of the intelligence community.
It was unclear on Monday whether cabinet would endorse the creation of a UK-style Home Office or make a more modest change to ministerial lines of responsibility for key agencies such as ASIO and the Australian Federal Police.
Malcolm Turnbull held discussions with British counter-terrorism officials - who operate under the Home Office - in London last week, telling reporters afterwards it was "no time for set and forget" when it came to national security policy.
On Monday, announcing law changes to make it easier for Australia's military to help police deal with terror attacks, the prime minister said again it was important to stay ahead of terrorists.
"We have to ensure that every resource we have - legislative, military, police, intelligence, security - is always at the highest standard and able to be brought to bear to keep Australians safe," he told reporters in Sydney.
Integrating departments such as attorney-general, Australian Federal Police, ASIO, Australian Border Force and immigration has previously been resisted in cabinet.
Foreign Minister Julie Bishop and Attorney-General George Brandis have previously argued those seeking change needed to demonstrate the existing system was not working, however Tony Abbott and Mr Dutton have advocated the mega-office approach.
Justice Minister Michael Keenan, who has also previously given the thumbs down to a Homeland Security agency, told reporters on Monday the decision was up to the prime minister.
"I want to reassure all Australians that the arrangements we have in place at the moment are exceptionally effective and the evidence for that is the fact we have stopped a dozen terrorist attacks from occurring on our soil," Mr Keenan said.
When he was opposition leader, Mr Turnbull described an Australian homeland security department as "a cheap copy of an American experiment".
A 2015 review of Australia's counter-terrorism machinery found a super agency "would likely be less, not more, responsive as large agencies tend to be less agile, less adaptable and more inward looking than smaller departments".
The review, conducted by former senior public servants Michael L'Estrange and Stephen Merchant, is also understood not to recommend a super-portfolio.
The prime minister on Monday unveiled a raft of changes to terror response arrangements, including having special forces provide specialised training to local police officers.
Citing recent attacks in London, he insisted police would remain the first responders to any incident, but it was time to increase co-operation with the military.
Defence will offer soldiers for embedding within police forces to bolster engagement between authorities.
The process involved in a military "call out" to an incident will be streamlined, including abolishing a provision that limits the states from asking for military assistance until their capability has been exceeded.
Labor is expected to support the new measures, but wants a detailed briefing.