"There's no doubt that this election, the second election a row that has had a focus on light rail, will certainly determine whether or not our city has this transport infrastructure," Mr Barr said.

Mr Hanson told Mr Barr he was trying to "con" people by suggesting light rail would cost $25 million – the amount Mr Barr has promised to spend in the next term on design work for the second stage from the city to Woden.

"You don't go into an election saying you're going to spend $25 million and come out the other end spending billions," he said, referring to Labor's promise at the last election to do design work on the first stage.

Mr Barr countered, "That my conservative opponent will continue to oppose every important piece of infrastructure investment in this city and any progress for Canberra we take as a given."

He said the Commonwealth Avenue bridge had the engineering capacity to take light rail and said the ACT would work with the National Capital Authority, which owned the bridge, to ensure it could happen.

"Its important to create a strong north-south transport spine for our city. It will shape the future development of Canberra ... our city can't go on sprawling outwards forever," he said, also suggesting the cost of the Liberals' plan to scrap the light-rail contracts would amount to $2000 for every household.

Mr Hanson said the Woden tramline would change the city's shape – driving development towards Adelaide Avenue. The Liberals wanted to rebuild the city centre rather than "gallivanting off to another development site".

The leaders regularly spoke over and interrupted each other, Mr Barr repeatedly referring to Mr Hanson as "my conservative colleague".

"Everyone in the heath sector, other than one doctor, is trashing your health policy," he told Mr Hanson. The Liberals' proposal for mini hospitals in Gungahlin and Tuggeranong were not real hospitals, were "dangerous", and were "a cheap political fix", he said. Mr Hanson said it was "outrageous" of Mr Barr to run a scare campaign on health.

They clashed also over poker machines, with Mr Hanson saying the Raiders would leave town if they lost poker machines when poker machines were allowed into the casino, a suggestion Mr Barr dismissed as "alarmist rubbish".

Asked about Labor's reliance on poker machines through its Labor Clubs, Mr Barr said the Labor Club was not making big donations.

Mr Barr said Mr Hanson led a team that included "hardline conservatives" opposed to abortion and same-sex marriage, and he pointed to Prime Minister Malcolm Turnbull as an example of what a moderate leader captured by the hard right looked like. Mr Hanson said he was a moderate and that he was not ashamed of the diversity in his party but embraced it.

Mr Hanson attacked Mr Barr over government land deals questioned by the auditor in a damning report last week, to which Mr Barr insisted the government put probity and integrity at the heart of what it did.

Mr Hanson said Labor still collected $266 million a year in stamp duty, which it would be transferred to rates. "We won't do that," he said. "That's not fair."

Mr Barr said, under the Liberals, stamp duty would increase with house prices, making it harder and harder to get into home ownership.

Labor's plan provided a secure revenue base. "Fundamentally, how can any government make decisions about the essential services that a community needs ... based on trying to guess how many houses will sell in this city in any given year?" he said.