NSW Nationals MP Leslie Williams has quit the party and intends to defect to the Liberals as the fallout from the koala policy saga continues.
In a statement, the Port Macquarie MP revealed she made an application to join the NSW division of the Liberal Party.
"Sadly, the events of the past weeks and months have cemented my decision to resign as a member of the NSW Nationals effective immediately," Ms Williams said in a statement on Sunday.
It comes after NSW Deputy Premier and state Nationals leader John Barilaro went on mental health leave on Friday following a torrid fortnight.
Mr Barilaro threatened to implode the coalition government if concessions were not made over the koala policy, which he described as a "nail in the coffin for farmers".
The Nationals are concerned changes to the Koala Habitat Protection State Environmental Planning Policy limit land use on farms and the ability to rezone areas for development.
He backed down when Premier Gladys Berejiklian gave him an ultimatum that either the Nationals MPs support the government or its ministers would be sacked from cabinet.
Ms Williams said she told the deputy premier last week she did not support his actions as they endangered the coalitions' "unprecedented investment across the Port Macquarie electorate".
"To put this in jeopardy and hold the premier and the government to ransom during this COVID-19 pandemic was unnecessary, unhelpful and frankly politically reckless and unreasonable," Ms Williams said.
"The events of the past week have represented a further example of a course of conduct and dealing that has once again effectively been condoned and failed to be addressed.
AAP has approached the NSW Nationals and Liberals for comment.
