“I don’t support a third chamber,” Morrison told Radio National host Fran Kelly on September 26. “It’s not a third chamber they’re talking about necessarily,” Kelly replied. “It’s a representative body.” “No, it really is,” said Morrison. On this point he was adamant. “People can dress it up any way they like but I think two chambers is enough.” The Uluru statement was not specific about the structure for this voice, although it is also true that advocates for the change say it is likely to be a national representative body to have a say on laws that affect Aboriginal and Torres Strait Islander people. What matters is that the Prime Minister has drawn a line that is impossible to cross in this term of Parliament. He regards the voice, written into the constitution, as unworkable.

This is a fundamental check on the mission set out by Indigenous leaders this week: “Voice. Treaty. Truth.” What is the chance of a treaty, or truth-telling about the past, if the voice does not have the constitutional power the Uluru statement demands? Loading Morrison’s words are also a check on the hopes aired when Ken Wyatt, the Minister for Indigenous Australians, told the National Press Club this week of his ambition for a referendum on constitutional recognition in this term of Parliament. The Prime Minister was not taken by surprise by Wyatt’s timetable. Morrison’s office was across the speech and the timetable for change. And it did not see any conflict between the speech and the ground rules Morrison set out last September. Yet the tone of Wyatt’s speech triggered alarm in the Coalition party room – a forum that is easily overlooked in all the talk of bringing the nation on the journey to constitutional change.

The concern among Liberal and Nationals MPs is about the scope of the amendment to the constitution. Many of them believe it is going too far to specify the “voice” and thereby set up a new power that could be expanded over time by the High Court. Loading This should not be dismissed as the minority view of a conservative wing of the Liberal Party. For some, it is a traditional Liberal position to guard against writing new powers into the constitution. There is no denying this obstacle, even if it is understandable for the advocates of constitutional recognition to emphasise the progress being made rather than the obstacles that lie ahead. When this newspaper reported the concerns of some MPs on Thursday, the response from one middle-of-the-road Liberal was instructive. He said the report had “barely scratched the surface” of backbench concern.

It might satisfy the party room to write a general recognition of Indigenous Australians into the constitution without giving the voice any authority or structure. Under this view, the voice could be established by legislation instead. But this option would fall short of the Uluru Statement and would hobble the government process before it even begins. The Uluru Statement from the Heart was released on May 26, 2017 by delegates to an Aboriginal and Torres Strait Islander Referendum Convention, held near Uluru in Central Australia. The message from Indigenous Australians is that the voice is not merely symbolic. “It is a proposal for hard-headed structural reform,” wrote Megan Davis, professor and pro-vice chancellor at the University of NSW, in The Australian Financial Review on Thursday. Davis welcomed the government’s commitment to a referendum and the “co-design” approach to getting a wide agreement on the constitutional amendment. “With Morrison’s support for the co-design process and commitment to a referendum, we feel positive and assured,” she wrote.

Labor Indigenous affairs spokeswoman Linda Burney is also more positive about the prospects for change – surprisingly so, given the warning signs from the Coalition backbench. Loading Burney says it is “absolute nonsense” to describe the voice as a “third chamber” and says it would be up to Parliament to establish the First Nations voice once the constitution is amended. The awkward truth, however, is that Morrison himself believes there is a risk of creating a “third chamber” and many of his backbench colleagues share this concern, which means they will resist the idea of spelling out a new power in the constitution. Who will give ground? There will have to be compromise on all sides if the nation is to avoid an impasse. For now, the proposals being put forward are so imprecise that nobody can be sure what it would mean in a referendum.