The NSW North Shore MP Felicity Wilson has unexpectedly won a fierce preselection battle by a single vote.
The sitting MP was tipped to lose the contest to Tim James, from the right of the Liberal Party.
Party branch members previously told the ABC Ms Wilson had lost their backing after failing to provide a complete account of her residential history and academic record.
Liberal sources told the ABC the result was strong validation of the Premier, who privately told MPs she was "delighted" with the outcome.
Party sources from the moderate faction said even a one-vote win is a fantastic result for the Premier.
They described Mr James as a "sore loser " given his suggestion he might challenge the outcome.
The ABC understands Mosman, Clifton Gardens, Mosman West, and Cremorne Point party branches were expected not to back Ms Wilson's preselection.
But she won 101 votes to 100.
Mr James is believed to be considering challenging the outcome because there were four informal votes.
The ABC understands he told preselectors he believed there were issues of natural justice at stake because of the invalid votes.
The outcome of the preselection battle is likely to be viewed as a big win for the Premier Gladys Berejiklian who had backed Ms Wilson.
The contest was being viewed as another test of the Premier's leadership.
Outside the meeting, Ms Wilson thanked her supporters, including the Premier.
"I'm so grateful for the party members that have come together tonight to make this decision for the future of North Shore and the Berejiklian Government," she said.
"I have worked so hard in what is 18 months and have been able to deliver real outcomes for our community of North Shore.
"I'm so glad that because of my party members' support I can keep getting on with the job tomorrow and every day and go back to my community in March next year and make sure that they know that I'll keep fighting for them, putting them first like the Berejiklian Government always does.
"I'm very grateful that you've put your support in me once again."
