Mr Rattenbury holds the balance of power in the ACT Parliament and any move to allow poker machines in the casino is likely to need his support, given the Liberals are opposed.

The Greens took a policy to the last election opposing any liberalisation of rules and supporting the restriction of poker machines to not-for-profit clubs.

But Mr Rattenbury said evidence now suggested that "it's not the number of poker machines in a venue, it's the number of venues which is an issue for problem gambling".

"That does raise interesting questions about is it best to have a whole range of venues spread throughout the suburbs where people can access poker machines, or is it better to have perhaps a smaller number of venues in concentrated locations," he said.

"... Clubs in the suburbs are positioned as family venues and families are invited to come to the clubs and yet there's a heavy presence of poker machines, it creates a normalisation around poker machines ...

"There is a debateable point here about is it better to have poker machines in a recognised gaming venue in the city or to have them dispersed into the suburbs?"

The Greens wanted clubs to reduce their reliance on poker machines, but it was also an economic necessity for clubs with poker machine revenue now falling.

"If they were to be able to sell some of their poker machines and use that capital sum to invest in revamping their club or some other source of income, that actually could provide them with windfall capital to effectively diversify their business model," he said.

The casino's bid for 500 poker machines is shaping as a big political issue for Chief Minister Andrew Barr, with strong opposition among some in the left of the Labor Party to the bid, but the business community equally strongly in favour. Mr Barr himself is open to the idea.

Lobbyist Richard Farmer, who helped conservative independent Paul Osborne and offsider Dave Rugendyke win two seats in the ACT Parliament so helping Kate Carnell form a Liberal government, is now fighting the casino bid for the Raiders club. Party left-winger and Labor Club board member Wayne Berry has also entered the fray, moving a motion passed by the club's board to oppose the casino bid.

But clubs are yet to use one of the biggest weapons at their disposal – a campaign harnessing their enormous reach into the community through their tens of thousands of members.

Canberra Business Chamber chief executive Robyn Hendry said the $330 million development would create jobs, attract visitors and bring locals to the city centre.

"Unfortunately while Canberra has a highly educated population, a socially conscious community, and is a clean, green and tech-savvy innovative city, this is not evident in the city centre – which requires some attention and investment," she said.

The Aquis Entertainment redevelopment offered "a large scale development that improves the city aesthetically, while bringing more activity to Civic by attracting people to visit, stay and socialise".

The bid looks unlikely to get Liberal support, with gambling spokesman Brendan Smyth saying the party was "firmly in favour of the community gaming model".

"The opposition does not believe the case for poker machines in the casino has been made," he said. "Furthermore, the opposition also has concerns that the Labor Party and the CFMEU are attempting to reap profits to the tune tens of millions of dollars out of any deal with the casino, which would be immoral and highly questionable."