The Australian Electoral Commission has raised the possibility that a record number of early votes will delay counting and make it more difficult to declare a winner on election night.
As the number of pre-poll votes cast this year surged past the 2016 record on Wednesday, commissioner Tom Rogers said "there may well be some delays" in announcing results on Saturday due to the additional complexity of counting such ballots.
The consistent rise in the popularity of early voting has prompted politicians to question whether the three-week pre-poll period needs to be shortened, and the issue will almost certainly be canvassed as part of the customary post-election review.
By Tuesday night Australians had cast slightly more than 3 million pre-poll votes, and that figure was expected to increase by another few hundred thousand on Wednesday - already exceeding the 2.98 million pre-poll votes lodged in 2016.
"Because a lot of those votes will be declaration votes and placed in envelopes, it just becomes more complex [to count]," Mr Rogers told the ABC on Wednesday.
Asked if that could delay results in crucial seats on Saturday, Mr Rogers said: "We're really hoping that's not the case but I'm cautioning everybody that it's a difficult thing for the AEC to do. It's a huge logistic activity. We'll be doing our very best but there may well be some delays on the night."
The AEC did not respond before deadline to questions about whether adequate preparations had been put in place for the expected increase in pre-poll voting.
Technically, voters are required to have a reason to vote at a pre-polling centre, such as work or travel commitments on election day that are unavoidable. However, in practice the requirement is rarely enforced.
The long pre-poll period has changed the way parties campaign, with big announcements shifted earlier in the campaign to ensure they reach people before they vote.
Former Liberal prime minister John Howard has cautioned against major changes to pre-polling, arguing voters have made their wishes clear by taking up the opportunity in such numbers.
But Treasurer Josh Frydenberg has said the three-week period "does feel a bit long" and will "probably be revisited by both sides of politics after this election".
MPs and ministers want the ability to get around their electorates and the country rather than manning polling stations for three weeks, he said.
- SMH/The Age