There has been a legal challenge, an Assembly committee, thousands of column inches and untold heartache expended in the war for Kingston Foreshore's Fitters Workshop.

Now the dispute looks set to cause a political crisis going to the heart of the Self Government Act, the nearest thing the ACT has to a constitution.

The bitter dispute in Canberra's arts circles over the future of the workshop has been raging since the building was ''discovered'' to be a ''unique musical space'', when it was used for performances in the 2010 Canberra International Music Festival, despite a deal having already been agreed to move visual arts outfit Megalo into the building.

As choral music enthusiasts from around Canberra took to Civic Square outside the Legislative Assembly yesterday to warble out their discontent, inside, the territory's three political parties were moving closer to a showdown over the future of the building.

A multi-party Assembly committee has recommended, with Labor dissenting, that the shed be retained as a ''multi-use'' venue and the musical groups have the ACT Greens and the Canberra Liberals - a majority on the floor of the Assembly chamber - onside.

Yesterday the Liberals passed a motion with Greens support calling on Arts Minister Joy Burch to act on the findings of the committee, a move the two smaller parties believe is binding on the minister.

But the government has other ideas, and insisted last night that it was not bound by the motion, arguing that under the Self Government Act only a minister had the power to spend money that had been appropriated. With neither side likely to back down, the issue looks set to emerge again in the last few sitting weeks of the seventh Assembly, with a showdown between the powers of the executive and those of the parliament.

Meanwhile the choral music enthusiasts gathered outside the Assembly to stake their claim to the workshop and sent the minister a simple message: this fight has a long way to go.

The groups fighting for control of the workshop for use as a choral music venue believe that the tide has turned in their favour.

A legal challenge in the ACT Civil and Administrative Tribunal to the renovations necessary to move Megalo into the building had a win last week, with the tribunal brushing aside a government attempt to block the case from being heard.

Yesterday, after tuning up in one of the Assembly's committee rooms - not a ''unique musical space'' - the choristers, who came from several different choirs around the city, took to Civic Square and burst into song.

Organiser Helen Moore said the key message was: ''Not happy Joy.''

''I felt the tide was turning when they set up the inquiry and I was really hopeful,because that was the first time that actual arguments were allowed to be presented,'' Ms Moore said. ''The evidence was overwhelmingly in favour of making that space a multi-use space.''