Peter Dutton has been more prudent than Anthony Albanese on budget policy with one measure. The opposition leader countered the prime minister in budget week by offering a $6 billion cut in fuel excise in response to the $17.4 billion personal income tax cut from Labor. The Coalition should be able to produce a better bottom line in its election costings. At the same time,however,Dutton repeatedly says he would consider extending the excise relief. He could throw fiscal rectitude out the window after victory.

The truth is that Dutton and Taylor have no convincing argument,at this stage of the campaign,about their capacity to build a stronger budget and a more resilient economy. Their pitch on Thursday,for instance,was about directing “windfall” revenue gains into a Future Generations Fund and a Regional Australia Future Fund. The two funds would receive 80 per cent of any gains in tax receipts above expectations – for instance,if iron ore prices are higher than the official forecasts (which is usually the case).

The weakness in this plan is obvious. The promise is to use the funds for several purposes – reducing debt,building infrastructure and creating jobs in the regions. So how much,exactly,would be used to cut debt? That will be up to the politicians. The idea looks like a way to replace Labor spending programs with Liberal and Nationals ones. A genuine pledge would be to make sure revenue gains fall to the budget bottom line so they could reduce the deficit or boost the surplus,and therefore pay down debt.

There is a lack of seriousness in these sorts of proposals. The press release sounds wonderful;the concept changes nothing. The national finances are now littered with off-budget funds that turn spending into an “investment” and transform debts into assets. The Future Fund stands alone as a significant achievement. The rest are dubious copies because they require the issue of more federal bonds so the money can be stored in a cashbox and spent on health,housing,clean energy,industry or other special programs. Each one has its merits. Put together,they offer new ways to disguise spending.

Dutton and Taylor could have set out a more rigorous approach to fiscal policy,but this would have meant giving up the “announceables” of the two new funds. They could have spent the past year using the resources of the Parliamentary Budget Office to explore a deeper rethink on spending and saving,but this would have entailed more political risk. In choosing not to take that risk,they lose traction when claiming they can offer a better way.

The Coalition’s biggest savings proposal,to cut 41,000 federal jobs,is certainly bold,but it is now beset by doubt. Dutton’sbackflip this week on working from home came with a clarification that the public service cuts would be achieved by attrition,not mass sackings. But how much,exactly,will this save over four years? That remains a secret. Dutton and Taylor have fallen into the habit of incremental revelation:they perform the dance of the seven veils with every policy.

It should have been possible for Taylor to rule out cuts to health and education – not just “guarantee spending” – when Chalmers asked the obvious question in their debate. Perhaps Taylor will do so in the weeks ahead. But the message on the night was that this remained an area of uncertainty in the Coalition budget policy,as if the commitments were yet to be nailed down.

Dutton has run a steady race for three years,and looked at times like he was trouncing Albanese,but he enters the final three weeks as the laggard. The key problem is policy. Dutton’s complaints about Labor were never going to be enough to speed him across the line,because all opposition leaders have to convince voters they have a better plan. They have to close the deal – and Dutton is running out of time to do it.

David Crowe is chief political correspondent forThe Sydney Morning Herald andThe Age.

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