There's method in National's madness

National took a calculated risk in asking Labour to join forces against New Zealand First leader Winston Peters to ram a message home to Tauranga voters.

It knew for sure that the approach would be premium-grade fodder in Mr Peters' campaign to pillory the "two old parties."

It also knew Labour would flatly reject the deal.

"What would Winston Peters most love?" said Labour leader Helen Clark. "Some thought of a deal between National and Labour to keep him out. I'm not falling into that one."

Labour could not remain credible and do a deal with the party it is trying to oust.

But National made the approach because it wanted exposure for the overtures by its candidate, Katherine O'Regan, to Labour's Margaret Wilson to ram this message home to Tauranga voters: the combined opposition to Mr Peters is greater than his support and could beat him.

The move launched National's 70 per cent campaign, which continues until election day. It is based on a Bay of Plenty/Key Research and Marketing poll in August that put Mr Peters' support at 31 per cent.

The tactic may steer a few uncommitted voters National's way but is unlikely to topple Mr Peters. That may not displease National too much, given that NZ First may be its only hope of regaining the Treasury benches.

National's bottom line in this exercise is to make sure it does not poll worse than second.

Tauranga was one of the truest of the blue electorates, electing National MPs from 1938 until 1993, when Mr Peters and National parted company.

Even at the last election, National topped the party vote and came second in the electorate vote. Coming third to Labour in either the electorate or party vote would be humiliating.