Vic leaders square off in election debate

After a bitter election campaign, Victoria's leaders showed unusual restraint in their first and only debate but they ultimately couldn't resist trading a few choice barbs.

Premier Daniel Andrews and Opposition Leader Matthew Guy were quizzed in a televised debate before 100 undecided voters at the Box Hill Town Hall on Tuesday evening.

After shaking hands and exchanging pleasantries, it took about half an hour for conversations to turn combative over the coalition's plan to quarantine all new gas discovered in Victoria for state-only use.

Labor has been running attack ads on social media in the lead-up to the November 26 poll claiming the Liberals will overturn the state's constitutional ban on fracking.

Host Kieran Gilbert asked the Labor leader whether he would commit to pulling the ads but Mr Andrews was adamant it wasn't misinformation.

"The chief scientist has made it very clear ... that there are no reserves of gas known or probable that can be extracted onshore using conventional methods," he told the crowd.

"The only way you can deliver a 'gas-led future' is to frack. That's just a fact."

But Mr Guy said another report from the chief scientist found up to 830 petajoules of onshore gas was ready and waiting to be unearthed through convention means.

"I'm not here for petty name-calling ... we're not going to frack," he said.

The Liberal leader said he didn't want to be drawn into a fight but the premier pushed on.

"It's not an argument. It's a debate and it's a pretty important point," Mr Andrews said.

Sparks flew soon after when the subject of integrity in politics was raised, with both major parties heading into the election with a corruption cloud over their heads.

If elected, the coalition has promised reforms to allow the Independent Broad-based Anti-corruption Commission (IBAC) to hold more public hearings.

Asked why Labor hadn't followed suit, the premier said he wouldn't cut across the corruption watchdog's independent processes.

"Due process is important," said Mr Andrews, who has been questioned in private by IBAC as a witness.

Mr Guy, who was last week referred to IBAC by the state electoral commission over a donor scandal, said a government he led would expand its powers no matter what.

"The state government in Victoria today faces more anti-corruption investigations than any government in this state's history," he said.

"They're the ones saying we don't want to give them the extra powers they're seeking."

A bemused Mr Andrews quipped: "Weren't you just bragging about the fact that you set it (IBAC) up and you were around the cabinet table? Isn't this your model? You can't have it both ways."

Earlier, Mr Guy was seeking to ram home Victoria's mounting debt, which is forecast to rise higher than NSW, Queensland and Tasmania combined.

"It's debt that will be around for our grandchildren," the aspiring premier said.

Seeking to make the election a referendum on health, the coalition has promised to shelve the Suburban Rail Loop (SRL) and redirect funds to the health system.

Mr Guy said voters should be wary of politicians telling them they can have everything, noting independent Parliamentary Budget Office (PBO) advice that the first two stages of the SRL would cost $125 billion.

"We have to make tough decisions," he said.

But Mr Andrews argued he has exhibited more restraint, pointing to PBO costings of promises showing the coalition has committed to spending more than $30 billion to Labor's $11 billion.

"We know who the spender in this contest is."

The people's forum vote gave Mr Andrews a narrow edge, scoring the debate 38 per cent to 34 per cent in his favour with 28 per cent undecided.