Julia Gillard is sometimes criticised for not appearing to stand for much. The same could never be said of Bob Brown. The Greens leader has had a very firm idea of what he wants, and now he has real power, he's determined to achieve as much of his agenda as possible, while understanding this requires a degree of pragmatism that wouldn't have been seen as a ''Green'' trait in earlier years.
To ''get things done'', as she would say, Gillard needs the Greens (and other crossbenchers), and after the new ''Green'' Senate comes in mid-year, the symbiotic relationship and what the Greens extract will be even more on display. The opposition constantly runs the mantra that Brown is the real PM, and recently the look has become unfortunate for Gillard.
''They hijacked the Prime Minister's courtyard,'' Tony Abbott harrumphed yesterday, referring to Green power being front and centre when Brown and his deputy, Christine Milne, stood with Gillard at last week's announcement of the carbon scheme.
But it was Milne's boast at the news conference that had some Labor people really squirming. The carbon price was happening ''because we have shared power in Australia'', she said. ''Majority government wouldn't have delivered this outcome. It is because the Greens are in the balance of power and working with the other parties to deliver, not only aspirations, but the process to achieve it.''
Milne's claim was bad for Labor because it played down the government's ownership of its own policy, and it played to the allegation that Gillard was the Greens' pawn.
Then, this week, Gillard was forced to backtrack over a Brown private member's bill to remove the power of the prime minister and cabinet to override laws passed by the ACT and Northern Territory, leaving that power solely with the Federal Parliament. This would make it harder in practice to overturn territory laws, because both houses would have to agree.
Tuesday's caucus unanimously approved Labor's support for this bill - in line with the stand Labor took on the issue in 2006 - and a Senate vote was due yesterday. But a revolt fomented when the Catholic right in the caucus became worried this would help the ACT's push to allow same-sex unions. Several senators fronted the PM: Gillard agreed the government would review its position after a Senate inquiry.
Gillard had been caught between the Greens bill - which, objectively, is perfectly reasonable and in line with Labor attitudes - and the social conservatism of a section of her own party. While the bill was about the territories' power to make their own law, the subtext was gay unions, an issue that the Greens have elevated.
The Greens have thoroughly wedged Labor on gay marriage. Adam Bandt, the Greens' sole lower house member, got through a motion calling on MPs to gauge their constituents' views on gay marriage - passed with Labor support, although ALP policy opposes it.
The profile the Greens have given the gay marriage issue has intensified the battle within Labor - it is now one of the headline items for the ALP December national conference, with the party split on principle and by the fears some have about the electoral damage that a change of position might bring.
Even a marginal issue can appear threatening when the ALP primary vote is in the pits and the carbon fight is assuming alarming proportions.
As Gillard strives publicly to defend the ''framework'' for her carbon scheme, behind the scenes the government has to negotiate a deal with the Greens that bridges the gulf between the minor party and industry over the compensation polluters will receive. The Greens want to be as tough on them as possible, while the government approach has to be more careful - being too hardline would be cutting its own political throat.
Gillard is sensitive to the allegation that she's under the Green thumb: she went out of her way yesterday to deny that any caucus member speaking to her about the territories bill had been objecting to the Greens influence. Indeed, ''no caucus member has ever raised such concerns with me''.
But how does she manage both the reality of Green powers and growing perceptions about it?
On the most important issue, carbon, her priority must be a deal that is sustainable from an economic and environmental point of view, and which is publicly saleable. If she leans too far towards the Greens, she risks being politically slain, first by industry and then by the voters.
Of course, there is a risk the Greens might thwart what they see as an unsatisfactory compromise. But they need to ''deliver'' as much as the government, and Brown is sounding very conciliatory.
On this and other issues, impressions are also crucial. This goes to the crux of the problem. Labor and the Greens have to work co-operatively now, but are electoral competitors later (but also, just to complicate the picture, dependent on Green preferences too). For Labor MPs in inner-city areas, that competition is potentially deadly - as the ALP found last year in the seat of Melbourne. That's why who gets how much credit and who's in the frame become important - and why the Milne statement was so galling for some Labor MPs.
Gillard has to make sure the minor players, especially the Greens, get enough recognition to keep them firmly in the cart. But if she lets them grab too much, her fragile authority will be eroded.
Put more bluntly, she needs to get across the message that she's the dog and they're the tail.
Michelle Grattan is Age political editor.
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