The Greens are hoping to retain two seats, and possibly gain another, at the October 17 ballot, which would likely hand them the power to effectively decide which party forms the next ACT government.

Mr Rattenbury said the party's election policy platform, which is headlined by a $400 million plan designed to tackle housing affordability and homelessness, would be the starting point for negotiations with the major parties on any potential power sharing agreement.

Mr Rattenbury and Labor leader Andrew Barr on Monday heralded another successful term of Labor-Greens government in the ACT, which included completion of the Gungahlin tram line and achievement of a 100 per cent renewable energy target.

The government failed to deliver on about 20 per cent of the proposals written into the power sharing agreement struck with the Greens after the 2016 election.

While it is likely the Greens would once again support Labor in a coalition government, Mr Rattenbury wouldn't rule out siding with the Liberals and Alistair Coe.

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"We don't presume to get that far ahead of ourselves - we need to see the outcome on polling day," he said. "We hope to have enough seats to play a role in the government going forward.

"Our members will play a really big part in that discussion as well. We will have discussions with members both before and after the election on what they want to see their parliamentary representatives do."

Mr Coe played down the prospects of a Liberal-Greens coalition, saying it was "highly unlikely" that the left wing party would support the Liberals into power.