The Australian Electoral Commission could have days to change its how-to-vote material for the voice referendum as an appeal over how 'X' votes are counted comes before a court.
United Australia Party senator Ralph Babet and the party's chairman, mining magnate Clive Palmer, have gone to the Federal Court seeking to have ballot papers marked with a cross counted as a vote against the proposed alteration to the constitution.
Last week, their case against the AEC was dismissed by the court.
On Tuesday, Senator Babet and Mr Palmer appealed this decision with the matter briefly coming before the Federal Court.
A full court hearing in front of a panel of three judges has been scheduled for October 9.
Representing the AEC, barrister Brendan Lim asked for the court to deliver its judgment by the 11th, three days before the referendum will be held.
Mr Lim mentioned "practical issues" the commission would face if the appeal was successful.
The AEC has already distributed advice telling people to make their vote count by writing in English either 'yes' or 'no' in the box on the ballot paper.
The commission has stated a tick in the box will count as 'yes', backed by decades of legal precedent across six referendums.
"The legal advice provides that for a single referendum question, a clear 'tick' should be counted as formal and a 'cross' should not," the AEC said in August.
Ballot papers marked with an 'X' would be considered informal and not be counted due to ambiguity about what that can mean.
The October 14 referendum ballot will present a proposed law to alter the constitution "to recognise the First Peoples of Australia by establishing an Aboriginal and Torres Strait Islander Voice".
Voters will be asked: "Do you approve of this proposed alteration?"
To pass, the referendum needs more than half of all voters and four of the six states to vote in favour of the proposal.
