Both major parties have lost more election candidates over social media posts making anti-Islamic statements and derogatory comments about women.

Mr Shorten was declared the winner of the debate in Brisbane, with 43 per cent of the undecided voters in the room picking him and 41 per cent picking Mr Morrison.

But earlier both leaders had to deal with more rogue candidates.

Liberal candidate for the Tasmanian seat of Lyons, Jessica Whelan, and Labor's candidate for Melbourne, Luke Creasey, were under pressure for days over posts they made on Facebook.

Ms Whelan resigned on Friday after admitting she made some anti-Islamic posts, while Mr Creasey quit over rape jokes and comments he made about watching a friend have sex.

Ms Whelan maintains one of the Islamophobic comments on Facebook under her name this week was "doctored" and has referred the matter to federal police.

But the Tasmanian Liberal Party says she has accepted she made "some of the other posts in question", one of which called for a national vote on banning Muslim immigration.

Prime Minister Scott Morrison quickly moved to distance his party from the Tasmanian, who still intends to run as an independent.

"Her views were her views, and they do not represent the views of the party I lead," he told reporters in Melbourne on Friday.

On the other side of the aisle, Mr Creasey withdrew from the contest for Melbourne over his 2012 Facebook posts even after he was backed by Labor leader Bill Shorten.

Mr Shorten initially described the remarks as "deeply offensive, shocking and stupid", but stood by the candidate.

But fresh posts emerged on Friday showing Mr Creasey had joked about watching a female friend have sex with multiple people and wanting somebody to "roughly take her virginity".

"I understand, especially as a member of the LGBTIQ community, that we need to be careful about what we share or like on social media," the fallen candidate said in a statement.

The Liberals had already lost lower house hopefuls Peter Killen and Jeremy Hearn this week, while Labor lost NT senate candidate Wayne Kurnoth, all because of online posts.

So far, 15 candidates have fallen by the wayside for a variety of reasons, including dual citizenship and inappropriate online comments.

Mr Morrison used the debate to attack Labor on its tax policy and promised to steward the economy through tough times, but Mr Shorten said Australia deserved better.

"Do you really think that life has been so fantastic in the last six years?" the Labor leader asked.

The two leaders stood in front of the crowd, and got a bit close at one point.

"You're a classic space invader," Mr Shorten told Mr Morrison.

Campaigning in Melbourne, the prime minister announced $203 million to protect Australia's waterways and threatened species, including a fund to develop more efficient ways of recycling.

Mr Shorten has vowed to set up a National Disability Insurance Scheme Future Fund to guarantee every dollar budgeted for the NDIS goes to the program.

He also promised to pump $2 billion into the Melbourne Metro Tunnel, Victoria's largest public transport project.

Australian Associated Press