But when Greens MLA Caroline Le Couteur went public with the idea on Monday, it shocked Liberals' housing spokesman Mark Parton, who had believed there was a rare chance for bipartisanship between the two opposing parties.

The idea is to allow landlords an exemption on land tax in exchange for cutting their rent to 75 per cent of the market rent, as long as the property was managed by a regulated community housing provider.

Not ground-breaking, and indeed, both ACT Treasury and individual landlords would take a hit in the thousands of dollars a year, if they took up the proposal.

But it remains a potentially easily-implemented financial mechanism which could help some low income Canberrans into more affordable housing, without the need for even greater government investment in bricks-and-mortar.

Ever since it was formally proposed in budget submissions and Estimates earlier this year, all parties have been sniffing around the idea.

But The Greens were the first to go public - with an announcement indicating the minor party wanted to ensure it happened pronto, rather than waiting around for the eventual release and implementation of the new affordable housing strategy.

Surely, they were on a winner - Mr Parton had already proposed strengthening their motion with his own amendment - and the government would not want to be seen not acting, so maybe everyone would endorse it.

That's the line, anyway.

But that is not how it played on the floor of the Assembly, with the Greens endorsing a government amendment to their own, to investigate the proposal and report back in October on the matter.

It meant rejecting the Opposition's potentially stronger-worded amendment, which was not ultimately moved in the Assembly, in favour of trying to deliver something more palatable to Labor, without actually requiring action by government to implement the proposal.

For Labor's, endorsing a more strongly-worded motion, or implementing the proposal, could expose it to yet more criticism from the union movement, after Unions ACT's public reaction to it, coming as the CFMEU looks to take the government task over wage theft allegations.

Some suggest it may have been political naivety, though that hardly washes when one considers Ms Le Couteur has served two terms in the Assembly, one as Assistant Speaker, and her boss, Greens leader Shane Rattenbury, has served nearly a decade in the chamber in roles including Speaker and several ministries.

Given the minor party had been in talks with both parties separately for at least a week beforehand, perhaps it was a more traditional move not to alienate their majority government partners further.

This is not the big house, where doing the numbers [once, twice, more if needed] on almost all major motions and bills in the Senate is an essential minimum of the political calculus.

The minor party had the numbers for whichever amendment it wished to support.

It also had a third option, not pursued, that it could have dealt with the Opposition to order the government to act on the matter, given motions do not bind the government to act, though the tax component and associated appropriation aspects may have complicated the matter.

In the end, it chose the government's.

The Greens now have a successful, if conditional, motion and Labor has agreed to examine the proposal in more detail with a cost benefit analysis, courtesy of a further Greens amendment to Labor's amendment to Ms Le Couter's original motion.

Ms Le Couteur told The Canberra Times before the motion was put, the party would be pushing for the government to enact the proposal. On the day of debate, she said there was "significant confusion" about the matter.

But The Greens' motion was couched in terms to 'consider' such action - a motion the Opposition believes was further watered down once the minor party agreed with Housing Minister Yvette Berry's amendment to investigate it - semantics.

Ms Berry has promised to consider it among the various proposals put to her for inclusion in the long-awaited affordable housing strategy - and it could be included in the final, funded, measures.

Yet it also may not, and if the strategy happens to be released before the first sitting week starting October 23, the motion could be rendered moot anyway.