Dutton declines to state position on voice referendum despite pressure on Liberals to decide stance

The opposition leader, Peter Dutton, has again declined to state his position on the Indigenous voice referendum, despite the Liberal party coming under pressure to decide its stance on the constitutional change now the amendment and question have been released.

Anthony Albanese has implored the opposition to support the referendum, but although he received a private advance briefing on the announcement and the design principles of the voice, Dutton has demanded yet more detail before picking a position. He said the Liberals want information on how the voice would improve the lives of Indigenous people.

“There is a lot of detail that has been requested and there are many more questions that have been posed today as a result of the third form of words put forward,” Dutton told a press conference in Canberra.

Related: The proposed voice to parliament question has been revealed. What happens next?

But Australia’s first Indigenous silk and member of the referendum working group, Tony McAvoy SC, said it is now “absolutely clear” that the parliament would have supremacy over voice advice.

“I’m confident that on an objective analysis, lawyers would be comfortable that the parliament has the ability to make legislation that goes to all the aspects of the operation and functions of the voice,” McAvoy told Guardian Australia.

The government’s proposed alteration to the constitution – to establish an Aboriginal and Torres Strait Islander voice that can make representations to parliament and executive government – will be formalised in a bill introduced next week. The government plans to pass the bill in June, and Dutton’s Liberals have said they will not be rushed into stating a position on the referendum until closer to the vote.

Some Liberals privately expressed concerns on Thursday that Dutton’s continuing doubts about the voice could see the party formally resolve to oppose the referendum.

Albanese gave Dutton and the Nationals leader, David Littleproud, whose party last year decided to oppose the voice without knowing any details of the government’s model, a briefing on the change ahead of a formal announcement. The prime minister said he was still seeking bipartisan support from the opposition.

“I’m hopeful and I have reached out consistently. It’s one of the reasons why we have been going through this process in a respectful manner. I would urge them to support it,” Albanese said.

“I would hope that this is an opportunity for a moment of national unity … there is an opportunity to wake up to a better Australia.”

The Nationals, One Nation and the United Australia Party reiterated their opposition to the voice.

The government’s agreed amendment has rebuffed concerns from a small number of conservative critics about the voice’s power to advise executive government. This was the subject of a proposed amendment from attorney-general Mark Dreyfus and solicitor-general Stephen Donaghue, which was roundly rubbished by the government’s referendum working group of Indigenous leaders.

Those concerns have also been rebuffed by constitutional lawyers including Anne Twomey, George Williams, Bret Walker, as well as former high court judge Kenneth Hayne and the former chief justice of Australia, Robert French.

Dutton demanded the government release legal advice from the solicitor-general about the executive government power. Without seeing the advice for himself, Dutton alleged the government had gone against the advice of the top law officer.

“If the prime minister has overridden the advice of the solicitor general, in favour of the view of the working group, then he should be upfront with the Australian public about why he’s taken that decision,” he said.

Dutton wouldn’t say if he used the briefing to ask Albanese for that advice, but Dreyfus said releasing the advice would be “inconsistent with the practice of successive governments over many years”.

Related: ‘I’m here to change the country’: Albanese launches an uncompromising Indigenous voice plan

“Some of the best legal minds in this country have been working on this. The Australian people can be confident that we’ve got this right,” he said.

The final wording was released on Thursday, after several last-ditch meetings between the working group and the prime minister. At an emotional press conference, featuring personal reflections from the Indigenous Australians minister, Linda Burney, and other Aboriginal and Torres Strait Islander community leaders, Albanese wiped away tears as he implored voters and the Coalition opposition to back the referendum.

When Australians vote at the referendum later this year, they’ll see a ballot paper with these words:

“This is a modest request. I say to Australia: don’t miss it,” Albanese said.

The proposed amendment, to be contained in a new chapter in the constitution, would establish a body known as the Aboriginal and Torres Strait Islander Voice. The advisory body would be able to make representations to the parliament and executive government.

The form of words settled upon, which took into account the concerns of the referendum working group, involved “robust but respectful discussion”, McAvoy said.

“I believe it is something that will have the ability to ensure that some of the structural obstacles, which have really been impossible for us to move, can be shifted. Those obstacles have weighed heavily on my family, my community. We find ourselves battling against those obstacles every day,” he said.

“As a lawyer who represents traditional owners of First Nations people across the country, it is a daily proposition that we must confront the policies and programmes which are designed about us, and for us, but always without us. This reform will ensure that we are at the table, able to speak for ourselves, in a way that we’ve never been able to before.”