ahead of former Wentworth MP Peter King, former Liberal Party staffer Mary-Lou Jarvis, former Woollahra deputy mayor Katherine O'Regan, who had been the expected frontrunner.

The ABC understands there were audible gasps in room when Ms O'Regan was knocked out of the running.

But the Prime Minister insisted today the party organisation had done its job in selecting the best candidate.

"What I would have been concerned about is if the Liberal Party didn't put its best foot forward in this by-election," Mr Morrison said.

"The party organisation gets to choose the candidates, [and] the Parliament party gets to do the work when it comes to the work of policy in government and otherwise.

"So, everyone did their job last night. They picked the best candidate.

"Every candidate who put themselves forward did thea huge amount for Australia. And I do want to honour him and acknowledge that debt," he said, flanked by the PM who replaced Mr Turnbull.

"With the support of the Prime Minister and other senior ministers, doing our best to keep Wentworth in Liberal hands."

Friendly rivalry

Outside the rugby club entrance before proceedings kicked off, Liberal Party heavyweights such as former attorney-general Phillip Ruddock and former Dreamworld chair Women's Weekly editor-in-chief Deborah Thomas entered the club to cast their vote.

Christine Forster, the sister of former prime minister Tony Abbott, walked in with her wife as a voting scrutineer for one of the candidates.

Ms Forster abandoned her tilt at the seat less than a week after announcing she would run, claiming her candidacy had become a "proxy for division" within