Hundreds of NSW Liberals will gather in Sydney on May 27 to endorse one of six candidates to replace the late Jim Molan.
Mr Brown, who heads the Space Industry Association and is a former NSW RSL president, has the endorsement of former prime minister John Howard.
He served in Iraq and Afghanistan, has worked on national security policy and continues to advocate for veterans through chairing the board of Invictus Australia.
Mr Brown is running as a factionally non-aligned candidate, which may go against him in terms of votes but is being promoted by supporters as a positive trait.
Factionalism was identified in an independent review of the Liberals' 2022 federal election campaign as a major problem in terms of the public perception of the party, delaying the preselection of candidates and preventing candidates from having a proper run-up time before election day.
Mr Constance represented the NSW state seat of Bega from 2003 to 2021 and served in a range of coalition government ministries including treasury and transport.
He ran for the federal seat of Gilmore last year but was defeated by Labor's Fiona Phillips by 373 votes.
Other candidates include former NSW Liberals president Maria Kovacic, former federal MP Fiona Scott, disability advocate David Brady and conservative-backed Jess Collins.
17°C