So, Labour has rejected an offer of a formal pre-election coalition and joint campaign from the Greens. Sadly, I'm not surprised. In the past, they've shown a preference for going right rather than left, and Labour's second-raters (who will lose out under any proportional Cabinet) have a strong reason to oppose formal power-sharing. But on any realistic numbers, its unthinkable for a future Labour government not to include the Greens, and as Gordon Campbell points out, by refusing to define their relationship themselves, Labour has given National a free hand to do it for them - and in undoubtedly negative terms. That won't do the Greens any harm: every time National says "the Greens will make Labour ban mining" or "the Greens will make Labour stop irrigation", its free advertising for them. But its unlikely to be good for Labour.