The NSW Liberal Party won't confirm whether Premier Dominic Perrottet told them about the Nazi costume during his preselection vetting process in 2010.
In a statement, the Liberal Party has told the ABC "the nomination process is confidential".
In the past, this process has included a panel interview by the Nomination Review Committee and in some cases has involved a third-party investigation.
On Thursday, Mr Perrottet disclosed that at his 21st birthday party in 2003, which had a uniform theme, he chose to wear a Nazi outfit.
In that same year, the now 40-year-old, became president of the Sydney University Liberal Club, and two years later was appointed president of the Young Liberals.
The premier said he only confessed to the "mistake" after a call from outgoing Transport Minister David Elliott.
In recent days, Mr Perrottet has apologised repeatedly at press conferences and in a video posted to social media — after first meeting with Sydney Jewish leaders following his disclosure.
He has also admitted it was something that "I had to carry with me for my life."
With the state heading to the polls on March 25, Charles Sturt University Professor Dominic O'Sullivan says the incident raises interesting questions about the party's checks and balances.
And if the premier's choice of costume was ever raised, "I think it should have been, and we don't know for sure that it wasn't," the political science professor said.
"If they decided it wasn't significant enough to disqualify him from preselection, then it would be interesting to know why."
Political parties make judgements when choosing candidates, which according to Professor O'Sullivan, should anticipate how voters will react and involve robust processes.
"Whether this should have stopped Perrottet's preselection is something we can speculate on, but it probably should have been thought about and put to some kind of test at the time.
"That may have happened, we don't know. But if it didn't happen, then it certainly would have been in the Liberal Party's interests to conduct that kind of test."
He points to the recent examples of disgraced former MP Daryl Maguire and Scott Morrison captain's pick for the seat of Warringah in last year's federal election, Katherine Deves, as "wholly inappropriate" candidates that slipped through the net.
"In the Katherine Deves situation … that was a risk that obviously the prime minister was willing to take, but a risk that many senior people in the Liberal Party thought was absurd.
"And the voters obviously thought it was absurd too when one looks at the election result in that electorate."
Voters will have the last say if, and how much, Perrottet's gaffe will influence their voting intention as the Coalition chases an unprecedented 16 years in power.
"I think in Perrottet's case, because this doesn't reflect a pattern of anti-Semitism — and a number of Jewish people have made that or similar points in the last few days in terms of the reasons they've given for accepting his apology — perhaps it wouldn't matter," Professor O'Sullivan said.
"But there are things that come up that point to somebody being a risk."
