The race to select a new Liberal senator is on the final stretch after Opposition Leader Peter Dutton endorsed former NSW treasurer Andrew Constance.
But the contest for the vacant NSW Senate spot created by the retirement of former minister Marise Payne remains open, as contenders try to cultivate the support of rank-and-file members.
Former ACT senator Zed Seselja, a staunch conservative who hails from the right faction, is contending for the spot alongside Andrew Constance, a moderate.
Mr Seselja lost his Senate spot to independent David Pocock at the last federal election, leaving the ACT without Liberal representation for the first time since the territory started with two senators in 1975.
Monica Tudehope, from the right, has also been touted as a strong contender and has the backing of Business Council chief executive Bran Black.
Ms Tudehope is the daughter of former NSW minister Damien Tudehope and worked as deputy chief of staff in both the premier's office and treasurer's office between 2017 to 2021 when the Liberals were in power.
Liberal Party sources believe Mr Constance - a close friend of Ms Payne and her husband, former NSW minister Stuart Ayres - is the frontrunner, especially after receiving the official endorsement of Mr Dutton.
"Having been a senior cabinet minister, Andrew has a wealth of policy-making experience," Mr Dutton wrote in a letter circulated to party members this month.
"In all the portfolios he has held - which traverse an array of economic and social policy areas - Andrew's approach was one which combined creativity, pragmatism and principle."
The opposition leader went on to call Mr Constance "a man of integrity who places great pride in putting the interest of the Australian people first".
"Should Andrew be successful in securing a Senate candidacy, he will be - as he has always been – a fierce defender of Liberal values at a time when they are needed most," he wrote.
"I am pleased to provide this reference for Andrew's pre-selection."
Mr Seselja has also seized on public comments made by the opposition leader, lauding his loyalty as well as praise from other coalition members including Tony Abbott and Jacinta Nampijinpa Price to push his case.
There are concerns from some moderates that complacency could lead to members backing other horses in early rounds and threaten Mr Constance's run.
Other moderates are pushing for former federal MP and ambassador to Israel Dave Sharma to take the spot.
But there is also a bid to have a regional-based senator after former party state president Maria Kovacic, a Sydney-based representative, was chosen to fill the spot of the late Jim Molan.
Mr Sharma hails from Sydney's affluent eastern suburbs and lost his seat of Wentworth to teal independent Allegra Spender last year.
Mr Constance, being based on the NSW south coast, would be in a position to help the Liberals contend the federal seats of Gilmore and Eden-Monaro at the next election, one source said.
The former NSW state treasurer lost his tilt for the seat of Gilmore at the 2022 federal election to Fiona Phillips by 373 votes, despite a 13 per cent swing to the Liberals.
The preselection ballot will take place in Sydney on Sunday.
