Bronwyn Bishop's parliamentary career looks to be over, after the former House of Representatives speaker lost a preselection ballot in her Sydney seat of Mackellar.

Former Liberal staffer Jason Falinski defeated Ms Bishop 51 to 39 in a meeting lasting five-and-a-half hours on Saturday evening.

The result will still need to be formally endorsed by the Liberal Party executive.

Ms Bishop, who has held the seat on Sydney's northern beaches for 22 years, left the meeting with a group of supporters.

"It's been an honour to serve the people of Mackellar," she told reporters on her way out.

Prime Minister Malcolm Turnbull thanked Ms Bishop for her service to the party, describing her as "unforgettable".

"Bronwyn is unforgettable. She's dynamic, colourful, charismatic and we thank her. On behalf of the liberal party we thank her for her extraordinary service," he said.

Before Saturday's ballot some party elders publicly criticised Ms Bishop's decision to recontest the seat, arguing it was time for the 73-year-old to retire and allow new blood into the ranks.

Mr Falinski said it was an honour to have been selected.

"I want to thank the Liberal Party for bestowing this honour on me," he said as he left the meeting.

"It is a privilege to be given their faith to represent the Liberal Party on the northern beaches. There's no other seat that I've ever wanted to represent in the federal parliament than Mackellar."

Mr Falinski also praised the outgoing MP for her "long service and dedication to the Liberal cause".

Mr Falinski, a moderate, and hard-right candidate Walter Villatora were widely seen as the biggest threats to Ms Bishop.

Mr Villatora was this week publicly endorsed by former prime minister Tony Abbott, who once described himself as the "political lovechild" of Ms Bishop and John Howard.

Bronwyn Bishop leaves the preselection meeting. ( AAP: Sam Mooy )

'Choppergate' sparked Bishop's decline

Ms Bishop resigned as speaker of the House after she billed taxpayers $5,000 for a short helicopter charter flight between Melbourne and Geelong, prompting a review of politicians' entitlements.

At the time, Mr Abbott stood by Ms Bishop, but joined NSW Premier Mike Baird in writing a refererence for Mr Villatora in February.

Professor David Flint, who is a friend of Ms Bishop, told AM she had done a good job in parliament, but it might be time to move on.

"She was certainly a very vigorous and strong member of Parliament," he said.

"There is a time, of course, when we all have to move on from our positions.

"She will be regarded very highly within the community, notwithstanding a minor peccadillo."

Mr Abbott posted a tribute to Ms Bishop on Twitter on Sunday.

"I thank Bronwyn Bishop for her service to the electorate, party and country for many years. She has been a warrior for good causes and deserves the gratitude of all members of the Liberal Party," he wrote.