Reduced to their essence, these are the competing visions ACT Labor and Canberra Liberals have put forward for the future of the Bush capital.

Andrew Barr's Labor is planning for a "compact" city, in which the rate of construction of apartments and townhouses in established suburbs vastly outpaces development on the suburban fringes.

Alistair Coe's Liberals, in contrast, want to release more land on the outskirts of the ACT for detached housing, giving more young families the opportunity to realise buy a home in Canberra, rather than in Queanbeyan, Googong or Yass.

Labor Planning Minister Mick Gentleman, the Liberals' planning spokesman Mark Parton and Greens leader Shane Rattenbury laid out their respective parties' visions for Canberra's future at an election forum hosted by the Property Council and Master Builders Association on Thursday afternoon.

Their audience was a selection of the biggest players in the capital's property sector: the developers, builders and consultants whose next four years will be framed, in part, by which party forms government after October 17.

Mr Gentleman, the territory's Planning Minister since 2016, said the election "will decide the future of Canberra".

The statement is self-evident, and typical of the "there has never been a more important time" rhetoric repeated throughout election campaigns.

But it does carry some substance given the clear divide between the major parties on planning Canberra's future.

A re-elected Barr Labor government would continue on the path mapped out in its 2018 planning strategy, the document which set the target for 70 per cent of all new dwellings to be built in established suburbs.

It would continue to sell single residential blocks in greenfield estates in Gungahlin, the Molonglo Valley and through its Ginninderry joint venture in West Belconnen.

Mr Gentleman told the forum that Labor's urban infill push would simultaneously provide "more high-quality living options", while preserving the bush capital's natural surrounds.

Two weeks out from polling day, and with thousands of Canberrans having already cast their vote, the Liberals are still yet to reveal the details of their planning policy.

However their overall policy position is clear: a Coe government would grow out.

Mr Parton said people in the suburbs were "hankering" to live in single-storey homes, but too many families were being denied that opportunity because of the high price of land and Labor's "fixation with growing up and not out".

"If things continue as they are many Canberra families will be forced to raise their kids in multi-storey complexes and their children will never get to play backyard cricket," Mr Parton told the audience.

"That may sound like a pretty small thing, but it's pretty important to me and it's extremely important to the many thousands of Canberra families who have chosen to fly the coop and build their house in Googong, Jerrabomberra, Bungendore and Murrumbateman, even Yass."

Mr Rattenbury, who supports urban infill, said Canberra needed to fill the so-called "missing middle" - a supply of townhouses and mid-rise blocks to suit buyers who either didn't want to live in, or couldn't afford, suburban homes or high-rise apartments.

The Canberra Liberals have made clear they want to open up more greenfield land for detached housing, but have so far refused to confirm how much and, crucially, where.

Their equivocations have left them exposed to attacks from Labor, who claim the Liberals are intent on transforming Kowen Forest and the grasslands west of the Murrumbidgee River in Tuggeranong into housing estates.

Mr Gentleman ratcheted up the pressure at Thursday's forum, saying the Liberals' position on certain policies - such as the 70 per cent urban infill target - would determine whether or not the ACT remained the bush capital or if it would develop "urban sprawl and congestion like western Sydney".

Mr Coe has all but confirmed one region that a Liberal government would redevelop: the large portions of land on the ACT's western fringe purchased in controversial circumstances by the Barr government's now-defunct Land Development Agency between 2014 and 2017.

"After all, ACT Labor paid top dollar in secret deals buying farms for land release," he said.

"So if you're going to spend millions and millions of dollars in secret deals buying these farms, you can at least make them available for Canberra families."

The Liberals are banking on the supply of more land for detached housing to help pay for their election promises, which according to Labor analysis would cost more than $1 billion over four years.

Mr Coe's "grow the pie" theory argues that if the cost of living was lowered - and that includes making housing more affordable - Canberra families would stay in the ACT rather than move to NSW, meaning their tax revenue would continue to flow into territory coffers.

The Liberal leader this week claimed the 2000 homes built over the border in Googong amounted to $400 million of revenue lost to the ACT. He even held up the number of ACT number plates outside the Googong sales office as proof Canberrans were being forced out of the territory.

Mr Barr has rejected claims of a Canberra exodus, pointing out that the capital's population has been growing at a quicker rate in recent years than its cross-border neighbours.

The Labor leader has also pushed back against the argument that the government - which controls the release of blocks to the market - has deliberately strangled supply of new land in order to drive up prices and profits.

Mr Barr this week maintained that the market ultimately determined land prices. The ACT government did its bit to support low-income earners by setting aside 15 per cent of dwellings at new estates for affordable housing, he said.

But it's not just Mr Coe is who using the ACT's land prices to sell themselves. Published on the Googong development's website is an analysis comparing land prices in the NSW suburb with lots in Coombs, Wright, Whitlam, Denman Prospect and Ginninderry.

"The amount of money you can save by buying just across the border is truly staggering," the website states.

The analysis showed that buyers would save more than $165,000 buying a 500-square-metre block in Googong rather than Denman Prospect. The research does not disclose that buyers of new blocks in the ACT don't have to pay stamp duty on their purchase until June 30 next year.

Housing Industry Association ACT regional director Greg Weller said the territory's land prices were likely to blame for the relatively low number of local applications for the Commonwealth's HomeBuilder program. The scheme provides grants of up to $25,000 to help people renovate or build a new home, provided the property is not worth more than $750,000.

Mr Weller said producing a clear, long-term land release strategy would help to provide certainty to the market and potentially help to improve housing affordability.

"What we don't want is an economy where there are people who can afford to live in houses and there are those who can't," he said.