Key Points:

Helen Clark's decision to relinquish the Labour Party leadership is said to have been made in the best interests of the party. It is hard to see how it could be so. Although it gives the country a clean break, her election-night announcement delivered a double blow to a party reeling from the electorate's rejection. It clearly took her colleagues by surprise. Jim Anderton said so. Party president Mike Williams was in a television studio and could not hide his dismay.

The decision allows Labour no time to find a promising successor. In the absence of a new face, it will probably elect the capable Phil Goff to lead it for the time being. Mr Goff has many of the attributes of Helen Clark: wide ministerial experience, a good command of all issues, instinctive common sense and a sure political touch. And he is a more forceful public speaker than she is.

But he is not much younger than she is, and as a minister in the 1980s has been on the national scene for just as long. He can never give Labour the fresh image a party normally needs to recover from a long period in power. By the next election Mr Goff would be in much the same position as Bill English was in 2002. As a leading minister in a recently defeated Government, Mr English could not lead National back to office.

Helen Clark's esteem within the Labour Party is such that she could have survived this defeat and probably led the party through three years of Opposition if she had wanted. With her experience and status she could have been very effective against a fairly greenhorn Government. If events were unkind to John Key, an electorate with a memory of better times might have returned her to power.

But plainly she did not relish leading an Opposition again and that can be understood. While the decision was timely for her and for the electorate, the party might have found it kinder had she waited long enough for a potential successor to emerge.

From Labour's point of view it would have been sufficient for Michael Cullen to step aside, as he is. An election for a new deputy to Helen Clark would have invited fresh blood to come forward and prepare the ground for a more orderly transition when the time was right.

As things stand now, the election of deputy leader might be more important than that of leader if Mr Goff is elected. The party would need a deputy younger, fresher, more interesting and ambitious to succeed him. And Mr Goff might be the only person who did not see himself as a caretaker. This sort of leadership is seldom in a party's best interests.

Already Labour's deputy leadership attracts more interest than Mr Goff's likely succession, though no fresher candidate has been found. Of Labour's recently rising Cabinet ministers, Maryan Street has declared herself unavailable and Shane Jones has just displayed some lapses in political judgment. David Cunliffe might be a better bet but he and Mr Goff hold neighbouring Auckland seats.

Beyond them, the only names suggested are familiar ministers such as Trevor Mallard and Annette King, neither of whom would have much new to offer, or the younger David Parker, who would not set the country alight.

The leadership of a major party can have a profound effect on the country's course. It is quite likely that Labour under new leadership would move further left than it could under any of those who have led the party in power. Mr Goff's succession would leave the policy fulcrum between the two parties much as it is. But that stability would be of limited value to the party or the country. If Labour elects him, it is already looking past him.