Election? What election? You could be excused for thinking that two rather pressing matters - a seemingly static poll rating and the onrushing election - might have sparked a tad more urgency on Labour's part regarding the unveiling of the core planks that would drive a Phil Goff-led government.

A week may be a long time in politics, but Labour has precious few of them left to acquaint the punters with its masterplan, let alone persuade enough of them of its merits to make for a serious contest on election day.

The Rugby World Cup kicks off in early September. For the following six weeks politics will truly struggle for coverage.

Politicians can go door-knocking at electorate level, but they will be wasting their time trying to attract the attention of the media, which will be firmly focused elsewhere.

By the time the official four-week election campaign starts a week or so after the final cup match, it may be too late for Labour to make serious inroads into National's lead, which is now between between 13 and 25 percentage points in the main polls.

Labour has to narrow that gap significantly within the next 10 to 11 weeks.

Yet it is not planning to start releasing major policy until around the middle of next month.

Goff is biding his time. Labour has its own timetable and it is sticking to it.

This seems to have little to do with the traditional opposition party's fear of fresh policy being stolen by the rival governing party.

It is certainly not the case on economic and tax policy as the two major parties head down increasingly diverging routes.

It does have a lot to do with the country's current straitened fiscal circumstances. Labour somehow has to make an electoral silk purse out of a revenue-deficient sow's ear. This takes time.

Labour has to get its numbers absolutely right - or its credibility will evaporate overnight.

It has two choices. The first is to live within the confines of National's broad tax settings, albeit with some tinkering of the top and bottom personal tax rates.

But because Labour is committed to paying off debt as quickly, if not more quickly, than National, the net effect of this would be that it would still have little cash available to pay for new policies.

Some flexibility might be achieved by reprioritising spending in some areas. Labour will do that.

But the big bills that have to be paid regardless - national super, hospital funding, benefit payments and so on - make this an exercise that can produce only small gains in savings, especially as National's cap on the funding of Government departments has made things so tight.

The spending constraints will also result in Labour phasing in some of its new policies over years rather than in one go.

There is also the matter of the gaping hole that will be left in Labour's balance sheet from National's banking of large portions of the money it expects to reap from partial sales of state-owned enterprises such as Meridian and Solid Energy.

This money - which could total about $7 billion - is designated for capital spending. As Labour says point-blank that it will not sell these assets, it will have to find the cash from other sources.

The net result of all this is to severely limit Labour's ability to present an alternative vision for New Zealand which will capture voters' attention without blowing the budget.

And if it goes down this path, Labour will be consigning itself to defeat.

Its vision has to be big and bold. And that requires taking the second choice - broadening the tax base to raise extra revenue.

That would require a capital gains tax or a land tax. Lifting the top personal tax rate on incomes above $100,000 simply will not raise enough cash.

Victoria University's tax working group estimated a capital gains tax, which exempted owner-occupied housing like the family home, could bring in close to $4 billion.

It would be a big call. Promoting a capital gains tax has long been seen as a ticket to oblivion.

But although the Greens are the only party openly advocating such a tax, politicians are these days less tentative about discussing the idea.

In 2009, Goff even offered Labour's backing for any National-initiated legislation imposing a capital gains tax on investment properties.

When asked since whether Labour would go it alone and introduce such a tax, Goff's replies have intimated the idea has been the subject of serious debate within Labour's policy machine.

Labour might add further exemptions to ensure the great bulk of low to middle-income earners do not pay the tax.

Labour's target is the well-off - especially those who structure their financial affairs to avoid paying any tax at all.

A capital gains tax fits perfectly with Labour's sloganeering that tough times require everyone to do their share to get the country back on its feet.

But selling a new tax during an election campaign is not a task for the faint-hearted.

While Bill English has made the occasional dispassionate remark about the virtues of a capital gains tax, National's natural inclination would be to rubbish it as as unworkable and punitive.

John Key has already been painting his party and Labour as "the politics of aspiration versus the politics of envy".

National would also see Labour's pushing of such a tax as further evidence - on top of its raising the minimum wage - that the old enemy is more concerned with keeping its base support than winning the election.

But National might well be misreading Labour's intentions. A capital gains tax would be the kind of big, bold initiative Labour needs to really shake up the status quo and make a fight of it.

And it might turn out to be the first of several if Goff is really going for broke.