Voters at the Indigenous voice referendum have been warned to reconsider wearing campaign T-shirts and badges into polling booths.
There is a long-standing rule banning campaigning inside polling places or within six metres of an entrance.
The Australian Electoral Commission said if a voter wore a pin, shirt or hat into a polling place it might not be considered campaigning.
But if the voter was seen talking about the material or gesturing towards it, it could be a breach of rules.
"AEC advice is to simply avoid any potential issue by not wearing campaign material into a polling place, or to at least bring along a piece of clothing that allows a voter to cover up," the commission said in its advice issued on Thursday.
Commission staff will take a "commonsense" approach to talking to voters about the matters, with people urged to be kind.
More than four million Australians have already voted before Saturday's referendum, which proposes changing the constitution to recognise Indigenous people and to enshrine an advisory body called the voice.
Polling shows the 'no' vote is ahead, but one in four voters are estimated to have yet decided how to cast their ballot.
Uluru Dialogue co-chairs Megan Davis and Pat Anderson said Australians had a history of backing underdogs and fair play over "negativity and spin".
"We remain incredibly optimistic - as optimistic as our old people were in the conversations we had throughout the regional dialogues process," Professor Davis said.
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