A Commission spokesman said the ballot officers had finished counting first preference votes for ballots cast on Saturday and for about 15,000 pre-poll ballots.

“We’ll be counting the preferences for postal votes until they stop coming in on Wednesday,” the spokesman said.

“The candidates’ preferences will be calculated at 9am on Thursday.”

The commission’s calculation of preferences is expected to serve as a de facto official result for the byelection, which has seen close margins between Liberal Julia Ham and independent Joe McGirr on first preference votes.

As of 5pm on Monday, Mrs Ham was in the lead by 11,982 votes to Mr McGirr’s 11,928, but most candidates urged their supporters to preference against her.

Labor’s Dan Hayes conceded defeat on Monday morning but Mr McGirr has said he will wait for the preference result. 

Mrs Ham has not conceeded but the Liberals suffered a 28 per cent swing against the party.