For many, Senator Bob Brown was the voice of the moral minority – someone who carried the uncompromising environmental message without the usual radicalism associated with it.

With his departure, his successor Christine Milne has rather larger shoes to fill. And while Milne may have the political experience to lead the Greens, she is a study in contrasts to her predecessor.

Brown was your astute politician, who exuded external calm, while retaining the ability to cut deals to progress causes the Greens believe in. That he single-handedly led the party from a one-man band to one that holds the balance of power in Canberra is testimony to his political skills.

Milne, on the other hand, has inherited the institution the Greens party is and while her political experience is not to be scoffed at, many see her as the “shrill lecturing mom”.

And despite being the spokesperson for the party, Milne has spent most of her political career in the shadows of Brown, starting from her political infancy in Tasmania to transitioning to federal politics.

For way too long Greens and Brown have been synonymous; it is now up to Milne to give the party a new definition.

But since assuming the mantle of the new leader, Milne is setting a tone to steer the party in a direction that could prove to be more radical. While she did say that she is committed to the deal that was struck with the Labor government, her actions seem to suggest a more hardline party approach.

As Milne embarked on a whistle-stop tour of rural Australia, her choice of the first stop was Orange, in New South Wales. Amid other concerns, the community in Northern NSW is worried about the increased spread of coal seam gas drilling activity.

Though she is yet to visit Queensland, the heartland of CSG activity, she did reiterate her opposition to CSG drilling.

“We have already had our state senators Larissa Waters and Lee Rhiannon visiting the Darling Downs and Liverpool Plains talking about coal seam gas and I will do what I can for farmers coming up against this industry,” Milne said shortly after being tapped for her new job.

It is this stand that will worry Labor. One could argue that much of the policy goals, including carbon pricing and a mining tax, that underpinned the Labor-Greens alliance have been achieved and that a seemingly unified front is not essential anymore.

Perhaps Labor realises this and with slumping poll numbers, it is increasingly seen to be distancing itself from the Greens. However, despite the Labor shift, its political fortunes are still intrinsically tied to the Greens.

Milne’s political position will be tested when the budget comes up for a vote next month.

The Greens have already voiced their opposition to tax cuts for big businesses as well as returning the budget to surplus through spending cuts just to meet political goals.

But what could prove to be a lightning rod issue is when the government reviews the federal Environment Protection and Biodiversity Conservation (EPBC) Act, potentially delegating approvals and assessments to state governments.

The federal government had last year said it would consider amendments to the Act to delegate authority and last week the COAG agreed to fast-track the development of bilateral arrangements to delegate federal assessments to the states and create taskforces for major projects.

And while the Coalition has indicated it would support such measures, any move by the Labor to strike a deal with them either on this or budget cuts, will unravel the already tenuous alliance with the Greens.

This article first appeared in ILN's sister publication EnergyNewsBulletin.net.