Three Liberal MPs are planning to move a spill motion against NSW Premier Gladys Berejiklian over the handling of the bill to decriminalise abortion.
In a joint statement issued on Monday night, state MPs Tanya Davies, Lou Amato and Matthew Mason-Cox said they had consistently requested that the premier urgently intervene and restore proper process on the bill.
They said their requests had been rejected and the lack of due process had broken trust within the Liberal party room and many communities across NSW.
"We have come to the conclusion that the right course of action is not to leave the Parliamentary Liberal Party but to hold the premier to account for presiding over this shameful process," they said in a statement.
The MPs said they would move a spill motion on Tuesday morning.
The sudden announcement comes a day before Upper house MPs start considering changes to the private member's bill on Tuesday, after some delay and a weekend of demonstrations from supporters and opponents of the draft legislation.
Tensions have simmered within the NSW government and the Premier Berejiklian has faced mounting pressure as opponents raise concerns about late-term abortions, conscientious objection, gender-based terminations and the way the bill was introduced.
Liberal MP Tanya Davies previously expressed her willingness to defect over the handling of the private member's bill.
The Reproductive Health Care Reform Bill 2019 passed the NSW lower house 59-31 in August with Liberal and Labor MPs having been allowed a conscience vote.
In its current form, the legislation would allow terminations up to 22 weeks, as well as later abortions if two doctors agree the termination should occur.
A group of upper house MPs, including the Shooters' Robert Borsak, One Nation's Mark Latham, Labor's Courtney Houssos and the Liberals' Natasha Maclaren-Jones, were expected to push a number of amendments this week.
Those who have demanded the withdrawal of the bill include ex-prime minister Tony Abbott and Ex-Nationals leader Barnaby Joyce.
"It is only with new leadership that we can again move forward as a united team delivering for the people of NSW," the statement from the three Liberal MPs said.
Deputy Premier John Barilaro in a tweet on Monday night said it was "ridiculous", adding "our coalition agreement is with Gladys and any move would be a dumb move".
Families, Communities and Disability Services Minister Gareth Ward also tweeted that Ms Berejiklian was the reason why the government had won the last election and "the reason why we'll win the next one".