This was the defensive note on which Scott Morrison began his regular post-national cabinet presser on Friday - and with good reason.

The prime minister has been under sustained pressure for the past few weeks to intervene in the growing chaos at state borders.

A string of senior Coalition figures have been lining up each day to kick state premiers, after knee-jerk closures have left agricultural workers stranded, families divided and children unable to access medical care.

Deputy Nationals Leader David Littleproud appealed to leaders ahead of national cabinet to allow "federalism to shine".

"Above all, we're Australians, and I'm just saying, this is the opportunity to prove it," he said.

But while the Commonwealth may be copping constant complaints about the continuing catastrophe, there is little it can do about it.

Domestic border closures are the domain of state and territory leaders - and as Friday's gathering showed once again, states will jealously guard their turf.

While Mr Morrison crowed about the breakthrough made on agricultural permits, with the cabinet to develop a code to allow farm workers to move through states and territories with the seasons, progress on a national framework for border closures remains stilted.

Although the national expert medical panel has been tasked with creating a definition of what a coronavirus hotspot is, Mr Morrison as good as admitted this would do little more than magnify when states aren't making logical decisions.

However, you don't need the nation's foremost medical minds to tell you declaring the ACT - the most consistently COVID-free jurisdiction in the nation - was purely a political decision.

And a political decision calls for a political solution.

The Commonwealth has few levers to pull on domestic borders, however, forcing states to shoulder more of the economic burden they are creating could reveal some of the decisions taken by state leaders as more parochial than driven by health concerns.