"I was advised late last night that I am now a member of the Liberal Party," the Port Macquarie MP told ABC News Breakfast on Monday.

"I've had many welcoming texts ... and I can assure my community that nothing is going to change. I'm going to continue to work hard and continue to make sure that they get what they deserve."

Ms Williams said people in her north coast electorate were "very angry" about Nationals leader John Barilaro's recent threat to the Berejiklian government to take his MPs to the cross bench over changes to the state's koala protection laws, which he described as a "nail in the coffin for farmers".

Port Macquarie has a koala hospital that treats hundreds of koalas every year and also is a big tourist attraction.

"I made it very clear to the deputy premier that I would not be supporting that action because I didn't think that it was going to achieve anything, and I think what we've seen over the past few weeks, in fact, that it has achieved nothing.

"What it has done is really put in jeopardy our relationship with our Liberal Party colleagues," she said.

She said other National MPs were unhappy about the public brawl.

"I can assure you that I know that there are some others, both members of the party and colleagues, who are feeling disappointed about what we've seen happen over the last couple of weeks," she said.

Mr Barilaro went on mental health leave on Friday following the torrid fortnight and Ms Williams wished him "all the very best".

"Obviously, it's been a challenging time for all of us," she said.

Mr Barilaro backed away from leaving the coalition when Premier Gladys Berejiklian gave him an ultimatum that either the Nationals MPs support the government or its ministers would be sacked from cabinet.

Australian Associated Press