Greens leader Senator Christine Milne has stunned Canberra by unexpectedly quitting her position. She has been replaced by Victorian Senator Richard Di Natale. The Greens hold the balance of power in the Senate and have caused the Abbott government considerable headaches by blocking its legislative agenda. The government needs support from six out of eight crossbenchers to pass any bill opposed by Labor and the Greens.

Treasurer Joe Hockey commented on Milne's resignation saying, "I don’t know the circumstances under which Christine Milne has resigned. I hope it is a retirement for all the right reasons rather than anything else but I just say to whoever is the new leader of the Greens: Please, please offer us some bipartisan work, bipartisan support in the Senate that helps us to strengthen the Australian economy."

“It is with a mix of optimism, pride, excitement and sadness that I am resigning the leadership and leaving the Senate," said Milne, who has led the party since 2012, in a statement. “My decision to resign today is one I made with my family. After 25 years in politics, I am looking forward to spending more time in my beautiful home state of Tasmania, with friends and family, and especially as I am soon to be a grandmother."

Milne said the Greens have stood strongly for a safe climate and an end to wealth inequality and "stood with the community against the cruelty of the Abbott Government, with their first budget resoundingly rejected by the people, and the Senate."

The new co-deputy leaders are Queensland Senator Larissa Waters and West Australian Senator Scott Ludlam.