After being Mackellar's sitting member for over two decades, Brownyn Bishop has lost preselection to Jason Falinski 51 votes to 39.

Part-time government staffer and aged care businessman Jason Falinski, who is in the party's moderate faction, won the majority of the vote after hours of deliberations at the Dee Why RSL club, where 96 NSW Liberal Party members convened to vote.

Ms Bishop went into the meeting without the endorsement from former Prime Minister Tony Abbott, who lent his approval to candidate Walter Villatora.

The former speaker didn't go down without a fight, making it to the the final round of voting in the marathon five-and-a-half hour long debate.

Jason Falinski still needs to be endorsed by the state executive as the official candidate, but he addressed media after voting ended.

'I do want to thank Bronwyn Bishop for her long service to the Liberal cause on the Northern Beaches,' he said.

Ms Bishop briefly spoke to reporters after the meeting.

'It's been a honour to serve the people of Mackellar,' she said.

The preselection process has also come under fire with some from within the NSW Liberal calling for reform.

Under the party rules, only 96 members were allowed to choose who will represent the Liberals at the next election.

Ms Bishop's formerly rock-solid standing took a hit last year when it emerged she has spent over $5000 of taxpayers money on a chartered helicopter flight to attend a Liberal Party fundraiser, a journey which would have taken an hour by road.

Despite paying back the fee and more, Ms Bishop resigned as speaker after losing the support of the then Prime Minister Tony Abbott.

Brownyn Bishop, 73, has a long political career, first joining at aged 17, she then became the first female president of the NSW Liberal Party before being elected to the senate in 1987.

The veteran politician served as Minister for Aged Care under John Howard before becoming the 29th speaker of the house of representatives in 2013.