Voters hand victory to Bill Shorten in first leaders' debate

Undecided voters have given the first leaders' debate to Bill Shorten as a record number of early votes were cast three weeks from the federal election.

Prime Minister Scott Morrison targeted Labor's tax and climate policies with questions about how much they would cost, which resonated with some voters at the debate.

But overall the majority of the 48 undecided voters in the debate, run by the Seven Network and The West Australian newspaper in Perth, gave the night to Mr Shorten.

A record 110,000 people cast early votes on Monday before the debate and Mr Morrison used that to demand answers from Labor on the cost of tax and climate policies.

"He's not telling you what the cost of change is," Mr Morrison said on Monday night.

"Voting has started, people deserve to know what the cost of change is."

But Mr Shorten said people were voting early because they wanted change, and that included action on the climate and healthcare.

"The cost of not changing is this: longer waiting lists," Mr Shorten said.

"I can categorically say that if we don't take real action on climate change that will be a disaster for our economy.

"This issue of ‘give us one number’, I don't think that's possible to do. If we want to stop polluting the environment, you have to spend some money."

Mr Morrison was asked why voters should trust the coalition after it tore down two sitting prime ministers in five years.

He said both parties had changed their rules to prevent more spills, but he pivoted to talking about the economy.

"The question of trust is the right one. Who do you trust to manage a $2 trillion economy?" he said.

Mr Shorten said Labor had been stable for six years and had put out policies well in advance of the election so voters could have faith in them.

Voter says Morrison ‘not on his game’

He also attacked the coalition for doing a preferences deal with Clive Palmer, who he said still owes taxpayers $70 million after he didn't pay workers their entitlements.

Of the 48 voters, 25 said Mr Shorten won, 12 picked Mr Morrison, and 11 remained undecided.

Voter John Hoolahan said he was still tossing up which way he was going to vote, but he said he thought Mr Morrison "was not on his game" in the debate.

"I still want to know where all this money is coming from that (Mr Shorten's) going to get from somewhere," he told AAP.

But he said Mr Morrison was not helping low-income earners.

Lisa Fieldhouse said she remained undecided and she plans to do more research, but Mr Morrison impressed her more.

"Bill Shorten didn't put dollar figures to things, even though he did push a lot of policy," she told AAP.

Another debate has been scheduled to be broadcast on Sky News from Brisbane on Friday, but the prime minister has already called for a third in prime time.

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