As the polls stand, all roads to a change of government lead through New Zealand First. And that makes the Greens little more than by-standers

It's not bad strategy, it's not bad planning. It's not their fault at all. But unless the polls move dramatically in the next few months, the Greens are backed into an uncomfortable political corner. New Zealand First has them by the, er, brussel sprouts.

Labour and the Greens simply aren't a viable two-party government as the polls stand, which makes New Zealand First simply vital to any potential change of government. While New Zealand First has left its options open re coalitions and there's plenty of smart money on Winston Peters' preference for backing National-led - or at least incumbent - government, any path to a change of government currently looks to lead through New Zealand First.

Labour's going to have to do some serious growing to find another path to government. So as it stands, if New Zealand First tells Labour it wants a formal coalition (something history tells us Peters prefers), but it will only consider a coalition if the Greens are excluded, well, Labour will have to exclude them.

What then do the Greens do? The Greens will of course argue back that they have a larger share of the vote than New Zealand First and that their numbers are still needed for a Labour-led government to reach 50 percent. But in fact all a Labour-New Zealand First government would need from the Greens would be confidence and supply; they don't need a full coalition deal.

When this scenario was put to Greens co-leader Metiria Turei on The Nation she said "if they [Labour] need us for confidence and supply, they need us to be government" and if the Greens are needed, "we, the Greens, are in a very strong bargaining position".

Except they're not. At all. If New Zealand First said they would only go with Labour if the Greens were sidelined and Labour bowed to that demand, the Greens would have two choices: Give confidence and supply to that government, or opt out and let a National-led government stay in power. Surely they couldn't let the latter happen, so they would have to allow themselves to be sidelined. Again.

And really, there's nothing they can do about it except hope that they or Labour start winning back voters.

At the same time Turei made it clear she would want to be co-deputy Prime Minister alongside Russel Norman in any Labour-Greens government. There's no rule against it, she said. It's worked well for the party, why not for the country?

Again, the road-block to that scenario is Winston Peters. If Labour and the Greens can't get a majority between them alone, New Zealand First can pretty much make whatever demands it wants, and almost certainly one of those demands would be the deputy Prime Ministership for Peters. And I can't see him sharing it in a three-way with the Greens co-leaders.

Every way the Greens seem to turn at the moment, they seem to come slap, bang up against Peters. Turei says the parties have worked well together, citing the likes of the manufacturing inquiry as evidence. But will that be enough to make New Zealand First want to change the country's direction? And what would New Zealand First voters make of that choice? Those are two more vital questions to ponder.