Bill English says he is still waiting for Labour to pledge to buy back the shares that National is planning to float in four state-owned companies. The Minister of Finance is waiting in vain. And happily so.

Labour is not about to shoot itself in the foot by dangling such an extravagant promise around its neck.

Knowing that making such a commitment is the last thing Labour will do, English can keep pinging the major Opposition party for not putting public money where its mouth is.

New Zealand First has no such qualms about forcing investors to hand back their shares and return the three electricity generator companies, along with the state coal company, to 100 per cent state ownership. That party appears to have decided it can afford to make such a lavish promise even if the country cannot.


Even so, you might think even New Zealand First would choke a little on the likely $5 billion to $7 billion bill.

However, Winston Peters' party can make such a credibility-straining declaration as it is unlikely to be the major partner in any governing arrangement post-2014 and thus not in a position to implement such a policy.

The irony is that the threat of a buyback may be the best weapon the Opposition parties have to stymie the share floats.

Investors might shy away from applying for shares if they knew they would be required to sell them by a Labour-led Government.

Labour's official line is that it cannot even contemplate a buyback when the size of the public floats and the price of the shares are still unknown.

With the proceeds from the sales likely to be long gone, however, any pledge to re-nationalise the companies now being readied for partial privatisation would cut right across Labour's efforts to portray itself as a careful manager of the economy - an area where it traditionally comes second to National in most voters' minds.

English's call for Labour to front up is an attempt to get on the front foot on an issue where National's stance is hugely unpopular.

National has been very much on the defensive during this week's lengthy parliamentary debates on the Mixed Ownership Model Bill which sets up the state-owned companies for partial privatisation.

To some degree, however, National has one hand tied behind its back. The party would love to be more fulsome about the details of the forthcoming offer of shares in Mighty River Power - the first candidate for partial sale.

However, under securities law, tight restrictions apply on what owners can say publicly about a share float in advance of the release of the offer document.

That is presumably why the Government is not confirming that the float will include the carrot of a loyalty bonus.

Such a bonus - which would reward shareholders with extra shares if they hang on to their initial allocation for a set period of time - is designed to answer critics who say small shareholdings will quickly end up in foreign ownership.

It might anyway suit National better to reveal such incentives when all the details of the share offer are unveiled.

National might have some clear air at that point. It does not now. National knew it would be on a hiding to nothing this week as it endeavoured to get the bill through Parliament and on to the statute books in quick time - thus removing what has been a valuable platform for those campaigning against partial asset sales.