Key Points:

The Labour Party's latest campaign to dent John Key's credibility has been described by some as an act of desperation to claw back lost support. Others see the oddest of spectacles, a governing party performing like an Opposition. Both were accurate perspectives on a small-minded assault that is more likely to buttress the National Party leader than undermine him.

Labour's tack this time, in what was largely a rehashing of old material, accorded huge significance to Mr Key's returns to the Electoral Enrolment Centre and the Companies Office in 2002. Health Minister Pete Hodgson said Mr Key had put different residential addresses on the documents, and effectively accused him of making a false or misleading claim to the Companies Office. He reminded Parliament that David Parker had lost his ministerial posts last year after admitting he filed false returns to that very office.

That may be so, but it ignores the fact that Mr Parker should never have been forced from office. His alleged offence was, at worst, a minor piece of business corner-cutting. After being quickly cleared by a Companies Office inquiry, he returned to Cabinet. Mr Key's conduct would be of much lesser moment, even if it constituted an infraction. As it is, Labour seems very much to have driven up a dead end street. An opinion from the Clerk of the House, sought by National, stated that the companies legislation did not affect Mr Key's registration for electoral purposes. Under the Electoral Act, a person can reside at only one place, but a person can have a number of residences for Companies Act purposes.

The National leader's character is being subjected to sustained attack by a party whose prospects look dim unless they can persuade New Zealanders that he is prone to indecision and contradictory statement. First, his stance on the Iraq war was placed under the spotlight. Now, Labour is seeking to incubate the notion that Mr Key deliberately misled Helensville voters about where he intended to live after the 2002 elections.

That hardly seems likely to have been a matter of overriding importance in the electorate. Or to voters throughout the country. What probably interests them more is the fact that the Health Minister has found time to collate the product of what he described as some "digging" by the party. Pressing matters related to waiting lists, overcrowded accident and emergency departments, and threatened industrial action by senior doctors were pushed to one side as this petty line of inquiry was pursued.

Two further allegations against Mr Key yesterday - that he is a director in a company involving two other people who, when unconnected to Mr Key, liquidated a firm facing a leaky building claim and that he was once interviewed by the Serious Fraud Office inquiring into a company's affairs - do not inspire greater confidence in Labour's tactics.

Encouragement for this approach may, initially at least, have come from the revelations of Australian Labor Party leader Kevin Rudd's drunken night in a New York strip club. Some saw this as manna for John Howard's Government, which also seems destined for electoral defeat. Yet polls suggest that Labor's standing with Australians had actually benefited from Mr Rudd's night out.

Character assassination is, therefore, a double-edged sword. It will backfire unless it produces matters of significantly more substance and seriousness than has been the case. Labour also risks, of course, firing too many shots now rather than trying to derail Mr Key when it really matters during a campaign proper.

Mr Hodgson's exercise in futility is evidence of a seriously distracted administration. A Government, in fact, that should get back to governing.