Retired Army major general Jim Molan is set to return to Federal Parliament after being chosen to fill the spot vacated by Liberal Senator Arthur Sinodinos.
Mr Molan defeated Insurance Council of Australia executive Richard Shields for the position at a meeting in Sydney today.
His pre-selection comes six months after he lost his Senate seat at the May election, having been relegated to an unwinnable place on the Coalition's New South Wales ticket.
Mr Molan angered some within his own party and the Nationals when his supporters ran a "below the line" campaign to try to get him re-elected.
However his pre-selection bid had the backing of high-profile Liberal figures including Prime Minister Scott Morrison and Home Affairs Minister Peter Dutton.
"He served his country in uniform and he's gone on very proudly to represent us in the Senate and I think he stands up for the vast majority of Australians," Mr Dutton told 2GB last week.
Senator Sinodinos is departing Parliament for Washington to take up the role of Australia's Ambassador to the United States.
Mr Molan was sworn in as a Senator for NSW in February 2018 after former deputy Nationals leader Fiona Nash was caught up in the dual citizenship scandal.
He previously served as Chief of Operations for the Coalition forces in Iraq and was the co-author of the Government's Operation Sovereign Borders policy.