Wentworth candidate Dave Sharma loses key support ahead of by-election

The former Australian Ambassador to Israel, Dave Sharma, has lost key support in his bid to be pre-selected for the Liberal Party in the seat of Wentworth ahead of the October 20 by-election. 

9NEWS understands the intervention of Prime Minister Scott Morrison, who has demanded a female candidate, has seen the NSW moderate faction fall in behind Katherine O'Regan. 

It’s understood Mr Morrison has relayed a message to moderates, through senior elected state figures, to back off in their support of Mr Sharma.

Mr Sharma is now being urged to pull out of the race, ahead of tomorrow's pre-selection, but it is still unclear if he will. 

While he doesn't live in the electorate, Mr Sharma is seen as "Cabinet material", with formidable credentials. 

Pre-selectors in Wentworth don't vote exclusively in blocks, and Mr Sharma backers believe he could thwart the prime minister's plan for a female, with a strong pitch tomorrow night.

A senior moderate power broker told 9NEWS the faction "supports the position of the prime minister", even though many of them have been working to secure Mr Sharma's numbers for the past week.

Mrs O'Regan is the former deputy mayor of Woollahra and worked for John Fahey when he was federal finance minister, a well as NSW Environment Minister Robyn Parker.

With factional support, it's now almost certain Mrs O'Regan will win. 

Mary-Lou Jarvis also has some support of "hard right" conservatives, but it's widely seen as not enough.

Other candidates are former member Tony King, Richard Shields, Michael Feneley and Carrington Brigham.

The pre-selection for the Liberal Party’s candidate for Wentworth will be held tomorrow night at Easts Rugby Club.