Prime Minister Tony Abbott says he does not believe Dyson Heydon should stand down as the head of the royal commission into trade unions.
Mr Heydon was due to make a decision on his future on Friday but has deferred his decision until Monday.
This was the second time the decision had been delayed this week, with Mr Heydon originally due to make a ruling on his position on Tuesday.
The latest delay comes amid fresh claims emails were withheld from union officials who have demanded the commissioner step down after he was listed as a guest speaker at a Liberal Party fundraiser.
Unions say Mr Heydon's acceptance of the invitation to the event suggests a political allegiance, and the royal commissioner himself will rule whether it's a case of apprehended bias.
Mr Abbott said on Friday he was confident Mr Heydon would act with the "utmost integrity" but did not see any need for him to resign.
"I don't believe there's any reason for him to stand down," Mr Abbott told ABC radio.
"Let's face it, serving High Court and Court of Appeal judges have actually addressed Labor Party gatherings and no one's thought that this was a cause to have them stand down or a source of apprehended bias.
"As soon as Dyson Heydon was reminded that this was actually a Liberal event, he withdrew."
Mr Abbott has not said whether the government is canvassing for a possible replacement for Mr Heydon, but both he and Opposition Leader Bill Shorten say the royal commission could continue under another commissioner if necessary.
"The royal commission will go on," Mr Abbott said on Friday.
"The royal commission must go on because what we have seen is an abundance of evidence, not just of corruption but even serious criminal influence in some unions.
"We just can't accept that."
ACTU national secretary Dave Oliver wrote to the commission on Thursday, asking it to urgently disclose further emails about what prompted Mr Heydon to withdraw from the event on the day Fairfax Media reported his involvement.
The call from the ACTU chief followed a report in The Australian on Thursday that suggested counsel assisting the royal commission Jeremy Stoljar, SC, may have alerted Mr Heydon to Liberal Party links to the event, named after former High Court chief justice and Liberal MP Sir Garfield Barwick.
The report said that Chris Winslow, the publications manager from the NSW Bar Association, had called Mr Stoljar on August 12 because he became concerned Mr Heydon's involvement in the event might soon appear in the media. Mr Winslow reportedly asked Mr Stoljar whether Mr Heydon knew the event was connected to the Liberal Party. Mr Stoljar is said to have replied: "I'll raise that with him."
The royal commission denied this, saying on Thursday that Mr Stoljar had only received an email from Mr Winslow asking him whether Mr Heydon knew about the Liberal Party connection.
"Mr Winslow did not communicate to Mr Stoljar that he had been contacted by a journalist or that he had a fear that a story about the matter might appear in the media."
The next day, August 13, Fairfax Media revealed that Mr Heydon had been listed as a guest speaker at the Sir Garfield Barwick lecture.
Soon after the report was published the royal commission released a statement saying that "prior to any media enquiry being received" Mr Heydon had "advised the organisers that 'If there was any possibility that the event could be described as a Liberal Party event he will be unable to give the address, at least whilst he is in the position of royal commissioner'."
