Former Speaker Bronwyn Bishop has been dumped by the Liberal Party as their candidate for the northern Sydney seat of Mackellar in the federal election.

Veteran Liberal Party member Jason Falinski was chosen in favour of Mrs Bishop, winning the ballot 51 votes to 39 in a hotly contested four-round pre-selection ballot on Saturday night.

The loss comes after Mrs Bishop was forced to resign as Speaker last year as a result of an expenses scandal over her use of a $5000 chartered helicopter flight to attend a party fundraiser.

She failed to gain the endorsement of former prime minister Tony Abbott, who instead backed close friend and conservative option Walter Villatora.

Jason Falinski with his family, arriving at the preselection ballot. (AAP)

Mr Villatora received just nine votes in the third round of voting, leaving Mr Falinski and Mrs Bishop the final two in the fourth round race.

A moderate and former Liberal staffer, Mr Falinski was frontrunner heading into preselection.

Deputy government whip Mark Coure was among the first to congratulate the new candidate.

"A great friend and mentor for over 20 years, who'll make a great contribution to federal parliament," he wrote on Twitter.

Labor used the preselection battle to highlight what it says is internal disunity and personal ambition in the Liberal Party.

"Wherever you look across the Liberal Party, from (Malcolm) Turnbull to (Scott) Morrison to Mr Abbott to Mrs Bishop, the Liberal Party is at war with itself," Opposition Leader Bill Shorten told reporters in western Sydney earlier on Saturday.

"You've got a Mr Turnbull-inspired candidate, you've got a Mr Abbott-inspired candidate and then you've got Bronwyn Bishop hanging on grimly to her position."

Preselection for retiring party stalwart Philip Ruddock's seat of Berowra was also decided on Saturday.

Julian Leeser, executive director of the Menzies Research Centre, won the vote on Saturday afternoon.

Bronwyn Bishop. (AAP)

"Congratulations Julian Leeser on an outstanding win in preselection for Berowra," Mr Ruddock said on Twitter.

Meanwhile, another long-time Liberal parliamentarian, Bob Baldwin, announced he will also bow out of federal politics in a bid to bring fresh faces into the house.

Mr Baldwin has been the member for Paterson in NSW for 17 years.