Prime Minister Scott Morrison and his rival Bill Shorten continued campaigning in Queensland after their second debate in Brisbane which the Labor leader narrowly won on Friday night.

On Saturday, Mr Morrison was spruiking a $100 million to boost hospital services in southeast Queensland, including a standalone urgent care service at Logan Hospital.

He also pledged $400,000 in annual funding for the Canefields Clubhouse, an organisation that offers a psychosocial rehabilitation program for people experiencing mental illness.

Troy Brown, a board member of the clubhouse, told the prime minister the number of lives lost from suicide is more than double the road toll.

Mr Morrison acknowledged the challenge, and spoke of his government's increased funding for youth mental health services, including through Headspace centres.

"There are just too many young people dying," Mr Morrison said.

The mood lightened as the leader, alongside his wife Jenny, took to a cake decorating table to have a crack at an activity performed at the clubhouse.

Mr Shorten was visiting Australia Zoo to announce a $1 billion package to protect the environment, including a new National Environment Protection Authority.

He said the funding would tackle the extinction crisis, cut single-use plastics, protect beaches and coastlines, clean up the nation's rivers, double the number of indigenous rangers caring for country, and protect the Great Barrier Reef.

"Australia's coastal communities are already seeing the impacts of climate change and rising sea levels, in increased coastal erosion, a loss of dunes and inundation," Mr Shorten said.

However, the leaders' announcements again risk being overshadowed by questions being raised about the suitability of more candidates on either side of the political divide after over a dozen have already fallen by the wayside.

Canberra candidate Mina Zaki is being scrutinised over whether she has properly renounced her Afghan citizenship, while Western Australian Labor candidate for the seat of Durack, Sharyn Morrow, could be under pressure over an anti-refugee social media post made in 2013.

Questioned about Ms Morrow's comments shadow treasurer Chris Bowen said it was the first he'd heard of her remarks.

"We have processes to look at these things. We would need to look at that closely," he told reporters in Sydney.

Mr Morrison and Mr Shorten clashed over tax, climate change and education during a sometimes heated second debate on Friday.

Of the audience of undecided voters, 43 per cent picked Mr Shorten, 41 per cent picked the prime minister, and 16 per cent had not made up their mind.

Meanwhile, independent MP Kerryn Phelps has questioned whether the three-week pre-polling period before an election is too long.

Pre-polling started last Monday for the May 18 election and according to the Australian Electoral Commission as of Friday 510,000 people had already voted, up from 315,000 at the same time in the 2016 election.

Dr Phelps, who holds the Sydney seat of Wentworth that was previously held by former prime minister Malcolm Turnbull, believes the AEC needs to look at the length of pre-polling for the next election, perhaps compressing it to one week.

She told Sky News people who vote in the third week or on polling day are voting on different circumstances that in the previous couple of weeks

Australian Associated Press