Audrey Young: National's leadership contest will be 'mercifully brief'

National leadership contender Bill English in full cry during today's urgent debate over Prime Minister John Key's resignation. Photo / Mark Mitchell

People almost always say leadership contests are healthy for political parties and almost always they are not.

They are damaging. Old enmities are revived and new ones created which are not necessarily forgiven.

It happened in Labour over three leadership contests - although Andrew Little has concreted over the cracks well - and it has already started to happen in National with MPs in a contest which pitches the backbench against the cabinet.

The one blessing for National is that the process is mercifully brief.

A risk in Jonathan Coleman's challenge, representing the younger political generation, is that it unleashes a resentment of the backbench against the Cabinet that cannot be undone.

Disunity in politics is lethal and voters can sense it.

The potential for damage is greater in a party that has had a remarkable record of discipline.

Bill English's performance since the Prime Minister's resignation announcement on Monday has only reinforced those who want change.

Apart from a lively contribution in a snap debate, he has talked about having energy but displayed little of it.

A revamp of the planning laws is hardly a strong campaigning platform.

English has left so much of the communication skills to John Key that he is out of condition.

English can be one of the most electrifying politicians when he wants; he can also be one of the most dull.

The greatest risk in Coleman's challenge is that he actually gains support over the week and wins in the vote next Monday.

It would be New Zealand's own version of Trump win - the greatest political upset in recent memory.

It would also humiliate English and could force him into a resignation as Finance Minister.

That would be almost as damaging as Key's departure, such is English's stewardship of the economy.

In announcing his candidature, English would not say what he would do if he lost.

He has every incentive not to say - staying on in the role would give Coleman a boost and saying he would resign would run counter to the interests of the party and look petulant.

But at some point, he may have to. A lot depends on it.