Bronwyn Bishop's decision to abandon Tony Abbott when his leadership hung by a thread is set to become a central issue of the Liberal preselection battle for her Sydney northern beaches seat of Mackellar.
Ms Bishop is facing an imminent challenge from hard-right forces loyal to Mr Abbott and still furious about the former Speaker's decision to vote for Malcolm Turnbull last September.
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Fairfax Media understands Mr Abbott's campaign manager and president of the Warringah federal electorate conference, Walter Villatora, is poised to enter the race for Mackellar.
Mr Villatora, an activist for democratic reform inside the Liberal Party, who worked as an adviser to NSW Premier Mike Baird during the state Coalition's time in opposition, has told a number of senior Liberals that he will contest Mackellar. Nominations close Friday at 5pm.
Mr Villatora, who did not return calls on Monday, has put his Manly home up for sale and, according to a report in a Sunday newspaper this week, is looking to move further up the peninsula into the Mackellar electorate.
A Liberal Party source said his involvement would make the breakdown of the Abbott - Bishop relationship a key part of the preselection and would have been unthinkable before relations soured between the long-term friends and electorate neighbours.
The "choppergate" scandal that engulfed Ms Bishop last year was considered one of the final nails in the coffin of Mr Abbott's leadership after he sustained weeks of political flak before moving her out of the Speaker's chair.
A source said: "A lot of her supporters [preselectors in Mackellar] found it very hard to cope with the fact that she didn't vote for Tony and instead chose Malcolm who supports things like same-sex marriage. Some were horrified and probably still are."
A Melbourne Cup field is likely to assemble in Mackellar despite no one yet publicly declaring their hand.
Among those known to be likely nominees are Jim Longley, the former state MP for Pittwater and Jason Falinski, a Liberal staffer and member of the dominant left faction of the NSW party.
Amanda Rawnsley, a senior adviser to NSW Family and Community Services Minister Brad Hazzard, former longtime northern beaches policeman David Walton and stockbroker Campbell Welsh are also rumoured to be considering a tilt.
Members of the centre right, the faction backing Ms Bishop, believe she enjoys the overwhelming support of her branches and will survive the challenge.
If she retains preselection, Ms Bishop could face an election challenge by Dick Smith. As revealed by Fairfax Media in January, Mr Smith, a childhood friend of Ms Bishop, is considering taking her on after being approached by a group of senior figures in the aviation industry urging him to stand.