NEW Greens leader Christine Milne pledged today she would not attempt to re-negotiate the deal which helped create the minority Labor Government.

Senator Bob Brown today announced his resignation, leaving politics with the Greens at a peak of influence in federal affairs and holding the balance of power in the Senate.

He told reporters in Canberra he had been mulling the decision since the 2010 election but had made up his mind during a trip to Africa.

"We came to the conclusion that this was the right time," he said, with partner Paul Thomas by his side.

Senator Brown, 67, said it was time for the party to renew itself.

The veteran environmentalist, who came to fame through his activism in Tasmania in the 1970s and 80s, said he believed the Greens would continue to grow in his absence but he would continue to take an interest in the movement.

"I will be a Green until the day I die, if not for a long time after that," he said.

Bob Brown resigns Bob Brown has resigned as leader of the Australian Greens parliamentary party.

Milne takes the helm

Senator Milne, Senator Brown's deputy, was unanimously endorsed as the new leader by the Greens party room.

Senator Milne said she was a signatory to the original agreement underpinning the minority Labor Government with her predecessor.

The pact to pursue a group of policy objectives - the biggest being the carbon pricing scheme to start in July - sparked Opposition claims the Greens were running the Government.



"There will be no renegotiation of the agreement that I'm already a signatory to," Senator Milne told reporters in Canberra today.

Bandt becomes deputy

Senator Milne said she looked forward to working with Adam Bandt as the party's deputy leader.

"Adam has a tremendous grasp of the issues confronting Australia, and I know he shares my passion to start a national conversation about what an Australian society values and wants to promote as we face the challenges of the century.''

Mr Bandt, who entered parliament as the member for Melbourne in 2010, said he was grateful for the party's support.

"I look forward to working with Christine Milne in providing stable leadership in this new phase in the growth of our party,'' he said.

"It will be a privilege and honour to work as deputy leader and support Senator Milne's vision, integrity and experience in minority government.''

No change to the carbon pricing

Senator Milne said she worked with both Liberal and Labor minority governments when Greens leader in the Tasmania Parliament.



There will be no change to the carbon pricing scheme set to start in July, and which Senator Milne helped draw up with the Government.



"Christine was the the instigator and the driving force for the carbon package," Senator Brown said.



"No one in this nation can have greater accolades for moving Australia into a reasonable direction to tackle climate change than Christine."



Julia Gillard might disagree.

'I intend to work as hard as I can'

The new Greens leader is not expected to deviate from the party's basic course set by Senator Brown, with whom Senator Milne has worked in state and federal politics for 25 years.



She said: "I intend to work as hard as I can with the Government and with the Parliament to deliver on the Greens objectives."



Senator Milne indicated she wanted to take the Greens, who have had most electoral success in inner cities, into the bush.



"Because rural and regional Australia has a critical role to play in this century, particularly in terms of food security in a global context, particularly in terms of renewable energy and energy efficiency," she said.



"Rural communities have been the backbone of environmental sustainability and protection and I'm going out there as a country person to say to other country people it's time that the Greens and country and rural and regional Australia really worked together."



She also wanted to work closely with "progressive business" on the opportunities rising from climate change issues.

- With AAP