Listening to Julia Gillard and Tony Abbott debating immigration and the anxieties of the outer suburbs, my mind went back to one dawn during 217 BC.

Hannibal lured his adversary into a long shallow valley along the shores of Lake Trasimeno after which his troops emerged from the fog and slaughtered an entire Roman army, driving it into the lake.

The Coalition’s populism on public debt sets a similar trap for them. But so far, for years and years now, the ALP has been so busy optimising the next 24 hours, so timid and reactive to the Opposition’s spin about “Labor’s debt” that it has missed the opportunity to emerge from the fog and dominate the next decade or so of politics.

While immigration can be a diversion, what the inhabitants of the outer suburbs really need and know they need — while they pay inflated tolls on stupidly privatised roads and wait in traffic jams — is old-fashioned government infrastructure.

The ALP has tried half-heartedly to make itself the party of infrastructure.  But without a chequebook, it’s largely spin.

But the alternative — higher debt — would be electoral poison, right?  Not if you set up the debate properly.  This is how the ALP could have already turned the situation around at the state and federal level.  There’s not time to do it before the federal election but there’s plenty of time after, and there’s time before all the state elections we’re expecting.

It could commission some independent economic worthy — say Bernie Fraser or Ian Macfarlane — to publicly define a responsible lending policy. And it could establish an independent agency to publicly advise on the responsibility of its fiscal policy and the cost effectiveness of its investments in infrastructure.

That could facilitate a large but economically responsible infrastructure spend around the country.  Tens of billions of dollars. When the Opposition cried “increased debt” the trap would be sprung. The government could point to its operating surpluses, the reports of the independent fiscal agency showing how responsible its debt levels were and how integral to higher economic growth. And over time it could point to the value of its investments (many of which would be privatisable and have market values well above their cost) and to the fact that its debt profiles were responsible.

But that would just be the beginning. Then it spends the next few elections pointing to all the infrastructure, including future projects and say to its opponents, “so you wouldn’t build that train line, that bridge, that overpass, that freeway?” and on and on.

Of course, there would be some critical comments in the first 24 hours. But done right, the Opposition would find itself fighting a losing battle — election after election.