Sources across the Abbott government have confirmed there had been internal consideration of a possible homeland security ministry – largely based on the US model – that could have been handed to Mr Morrison, rather than Defence Minister David Johnston. It is an idea that past governments have rejected on at least two occasions. Sensitivity to the mooted pre-positioning reveals previously unknown anxieties within the Abbott cabinet over the future succession of several potential contenders – a field that contains Mr Morrison, Treasurer Joe Hockey, Foreign Affairs Minister Julie Bishop and former leader Malcolm Turnbull. Critics of Mr Johnston say he has been disappointing in the Defence job, while supporters argue that his low media profile has left him open to that complaint despite his strong performance. Backers of the high-profile Mr Morrison point to his success in "stopping the boats" through his focused use of the single operational model under the name "Operation Sovereign Borders".

Mr Morrison has established a reputation for "tungsten" toughness and dogged commitment to purpose in the border protection portfolio in the face of widespread community criticism. But the argument over the respective career prospects of the two ministers is only part of the story. It is understood that the new ministerial structure is favoured by several others including junior ministers and those on the "apron" of the ministry who might stand to gain either directly from a post in the new portfolio or from the broader ministerial reshuffle that its creation would necessitate. The super-ministry idea was all but killed off in recent days when Ms Bishop, the Liberal Party deputy leader, said it was not needed because no substantial problems had been found. Ms Bishop, who has overseen the merger of Australia's foreign assistance arm AusAid with the Department of Foreign Affairs and Trade, knows firsthand how difficult such administrative aggregations can be to manage.

She has warned colleagues that undertaking a far more extensive re-organisation of multiple agencies would be an enormous distraction and a significant expense at a time of great difficulty and budgetary stress. Senior government figures have told Fairfax Media the review of Australia's counter-terrorism machinery, which is due to conclude by the end of the year, was not focused so much on "who does what" but rather on co-ordination between security agencies. While there could be a rearranging of ministerial responsibilities that would hand additional responsibilities to Mr Morrison, there are also suggestions a new official could be appointed as a counter-terrorism tsar. The possibility of a Department of Homeland Security being created is said to be all but dead. The implementation of Operation Sovereign Borders has been held up as an example of a successful organisational structure with government.

The bureaucracy's slow reaction to the downing of flight MH17 has in part triggered the review. Similarly, there is a strong view in the Abbott government that the bureaucracy is not ready or structured to handle the emerging terrorism threat. The entire issue is tied up with the timing of a reshuffle that will eventually be necessary one way or the other because of the temporary and possibly permanent vacancy created by the absence of Assistant Treasurer Arthur Sinodinos. He awaits the findings of an Independent Commission Against Corruption inquiry due next year. Follow us on Twitter