The NSW Liberals had plenty of time to nominate candidates for local government elections, the state's electoral commission says, rejecting a requested deadline extension despite its own formal election notice being published two days late.
There was still no "realistic possibility" the party or its candidates would not have known the deadline, the commission said.
The stoush escalated on Sunday as the party threatened legal action, labelling the rejection of the sought extension a threat to democracy.
The Liberals were left red-faced after failing to submit up to 151 nomination forms for local elections being held on September 14.
A subsequent request by state president Don Harwin to extend the nomination period was rejected by acting NSW electoral commissioner Matthew Phillips.
The party pointed to a "significant error" in the commission formally calling for nominations five days before the deadline, when it needed to be at least a week.
"This mistake is not just a technicality - it goes to the heart of ensuring a fair and transparent election," the party said.
Dr Phillips accepted the notice was published five days prior to nominations closing, but says the commission first published the nomination date on its website in October.
"It had also communicated this information directly to parties and candidates on numerous occasions since May," the commission said in a statement.
"The commissioner does not consider there could have been a realistic possibility that (Liberal) officials ... or persons proposing to run as candidates endorsed by that party, could have been unaware of the nomination day," it added.
The party said it would be left with no option but to pursue legal action if the commission refused the extension.
"Voters across NSW deserve the right to choose from a full range of candidates, including those endorsed by the Liberal Party, rather than being limited to an economically reckless Labor Party or a radical Greens agenda.
"Not allowing Liberal-endorsed candidates back on the ballot is bad for our democracy," the party said in its statement.
Dr Phillips was not satisfied it was possible to lawfully extend the nomination period.
"Even if it were, it would not be appropriate to do so given the very significant ramifications it would have for the conduct of the elections," the commission's statement added.
Former NSW Liberal premier Mike Baird said the administrative stuff-up was hard to believe.
"I'm heartbroken because I know many candidates who have put their heart and soul into communities and they're not going to be given a chance - and that's a tragedy," Mr Baird told reporters on Sunday.
"They have to get to the bottom of how it happened and make sure it never happens again."
Prime Minister Anthony Albanese described the threats of legal action as farcical.
"Legal action is just stringing out what was a complete stuff-up," Mr Albanese told reporters.
"If you can't even get your act together to nominate for council elections, I think it says everything about the dysfunction that's there in the Liberal Party."
