NSW Premier Gladys Berejiklian has sacked Parliamentary Secretary for the Hunter Catherine Cusack after she voted against a controversial land management bill.
Ms Cusack, who has been a member of the NSW Legislative Council since 2003, voted to have the Local Land Services Bill amendments sent to a committee, sparking an angry response from Ms Berejiklian, who had hoped to end tension within the government over koala planning policy.
Ms Cusack's vote on Thursday night saw the bill go down 18-19, meaning it is unlikely to get the green light until well into next year.
"Following her decision today to move a non-Government amendment to a Government bill, I have made the decision to immediately remove Ms Catherine Cusack as a Parliamentary Secretary," Ms Berejiklian said.
A spokesperson for Ms Cusack said she didn't wish to comment on Thursday night.
Earlier, in parliament, she apologised "to the Premier, my party and our coalition partners" for voting against the coalition, saying her "faith in the processes has been shattered".
Port Stephens MP Kate Washington, who has clashed with Ms Cusack in the past, supported her actions on Thursday night.
"There is no love lost between Catherine Cusack and I. Her behaviour towards me at the last election was appalling. But her decision today was the right decision. Thank you," Ms Washington tweeted.
Greens MP Cate Faehrmann, who chairs the NSW Upper House Inquiry into Koalas, celebrated the vote.
"Fair to say the Nats Koala-Killing bill has been killed! Woot!!" she posted on Twitter.
Last month, it appeared the stoush over koala protection policy that almost tore the NSW coalition government apart was over, with cabinet finally agreeing on an amended set of rules and Ms Berejiklian describing it as a balanced outcome.
In September, NSW Nationals leader and deputy premier John Barilaro threatened to blow up the coalition government if concessions weren't made to rural property owners.
He argued the laws were a "nail in the coffin for farmers" and threatened to take his MPs to the cross bench, but backed down less than 24 hours later after an ultimatum from the premier.
The Nationals wanted several changes made including the removal of the controversial koala mapping, which has now been taken out of the policy.
They were also concerned the policy would limit land use on farms and the ability to rezone areas for development as more trees would be classed as koala habitat, which would restrict clearing.
A refinement of the definition of "core koala habitat" was among the changes approved.