Malcolm Turnbull and Bill Shorten will face off in the first debate of the campaign on Friday, as the prime minister's business interests became an election issue.
Labor says Mr Turnbull has questions to answer over his name appearing in the so-called Panama Papers, despite the prime minister saying there is not even a "suggestion of any impropriety".
The call came as Bill Shorten's judgment was questioned after the sacking of a West Australian Labor candidate who had been endorsed despite having prior criminal convictions.
A document shows Mr Turnbull was the former director of Star Technology Systems Limited in the 1990s, along with former NSW Labor premier Neville Wran.
Both men resigned their directorship of Star Technology in September 1995.
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The company was incorporated by Panamanian law firm Mossack Fonseca, a secretive company involved in setting up thousands of offshore shell companies.
Mr Turnbull, who has been the subject of past Labor attacks over his corporate links, told reporters at a craft brewery in Melbourne on Thursday there was no suggestion of wrongdoing.
"The company concerned was a wholly owned subsidiary of a publicly-listed Australian company," he said.
"The involvement is very, very well known and ... there's no suggestion of any impropriety at all."
Mr Shorten told reporters in central Queensland the prime minister had "serious matters to answer".
"I think it is incumbent upon him to do so fully," he said.
Treasurer Scott Morrison said Mr Turnbull was someone with a "lot of experience in supporting businesses", which was what Australia needed.
"He has invested in them, he has created them, he has employed people over his lifetime," Mr Morrison said.
Mr Shorten's campaign was "running off the rails" in the wake of its Fremantle candidate, maritime unionist Chris Brown, being sacked for not disclosing two now-spent convictions for assault and drink-driving, Mr Morrison said.
The Labor leader said it was disappointing, but the party had now acted to appoint a new candidate, Fremantle deputy mayor Josh Wilson.
Mr Shorten, who turned 49 on Thursday, was joined on the campaign trail by his wife Chloe as they visited schools to talk about education funding.
The two leaders will take part in a televised debate in western Sydney on Friday night.
Veteran Labor strategist Bruce Hawker said the debate would favour Mr Shorten as "for the first time the opposition leader is on exactly the same footing as the prime minister".
"In terms of personal appeal, Shorten is coming from behind and he has everything to gain and nothing to lose from a good performance," Mr Hawker told AAP.
He said Mr Turnbull's challenge is being a "progressive prime minister in a conservative party".
"He will need to deal with that because it's an authenticity issue for him."
