Former Operation Sovereign Border special envoy Jim Molan will return to the Senate after the Liberal Party backed him to take the vacancy created by Arthur Sinodinos' departure.
Mr Molan was elected to the Senate in December 2017 after former Nationals deputy leader Fiona Nash was forced out during the dual citizenship scandal that year, but was placed in an unwinnable position for the May federal election and subsequently lost his spot.
But the Liberal state council held in Sydney on Sunday endorsed Mr Molan over his closest rival, insurance industry lobbyist Richard Shields, 321 votes to 260 votes.
The two-year vacancy was created after Prime Minister Scott Morrison appointed Mr Sinodinos to be Australia's Ambassador to the United States, succeeding former treasurer Joe Hockey.
The vote was widely seen as a test of Mr Morrison's authority, with Mr Molan unpopular among the party's Moderate and Right factions after running a "below-the-line" campaign at the election.
However, the Right did formally endorse Mr Molan after an intervention from Mr Morrison and other Liberal heavyweights, including former prime minister John Howard.
Mr Molan received 277 first preference votes to Mr Shields' 153 while 81 votes were cast for St Vincent's Hospital heart surgeon Michael Feneley.
Former Liberal MP Peter Hendy, who went on to be a senior adviser for Malcolm Turnbull and secured the backing of former foreign minister Alexander Downer, received five votes.
Mr Molan has previously spend decades in the Australian Defence Force, including as chief-of-operations during its 2003 deployment in Iraq.
He was dropped to an unwinnable position on the Coalition's Senate ticket in May after losing a preselection to the Centre Right's Hollie Hughes and the Moderate faction's Andrew Bragg.
- SMH/The Age