The yes campaign for an Indigenous Voice to Parliament has been bolstered by the official backing of the federal Greens.

Leader Adam Bandt made the announcement following an evening party room meeting after outspoken First Nations senator Lidia Thorpe quit the party over the issue.

Senator Thorpe said she wanted to campaign from the cross bench for “black sovereignty” beyond the Voice proposal.

While critical of the Voice’s proposition, saying she wants a First Nations treaty first, Senator Thorpe said she wouldn’t yet announce her position on the referendum.

But Mr Bandt confirmed the party would be supporting a yes vote at the referendum to establish an Indigenous Voice to Parliament.

“We want the referendum to succeed, we want First Nations justice and we want truth and treaty as well as voice,” he said.

“A strong First Nations body would be a further step towards true self-determination and justice.”

Mr Bandt said the party had secured commitments from the government that they would proceed with both truth and treaty as well as the Voice.

“I don’t think a ‘no’ vote will get us closer to treaty and truth, but I respect that others in the First Nations community may have a different view on that.”

The Voice dominated the first day of Parliament, with Prime Minister Anthony Albanese again urging Australians to support the body.

Mr Albanese used the first day of Parliament for the year to urge support for an Indigenous Voice.

He said the Voice to Parliament, which will be put to a referendum later this year, should be above politics.

“We need to get the detail right and there would be a process, as well as that parliamentary debate about the legislation, and I’d want to get as much agreement as possible,” he told reporters in Canberra.

“I want this to be a long-term reform to benefit Indigenous Australians, to help close the gap.”

However, shadow attorney-general Julian Leeser called for the Voice to also work alongside tangible outcomes to improve Indigenous lives.

“Symbolic change and practical outcomes do go hand in hand. It is a reason why I am a supporter of the idea of a Voice,” he told Parliament.

“I am deeply concerned about where this debate is at. The government is tripping over itself on the lack of detail. The government is mucking this up. The lack of detail is damaging support for the Voice.”

The latest Newspoll indicated 56 per cent of respondents supported the Voice while 37 per cent were opposed.

“Polls come and go – what matters is when people cast their vote,” Mr Albanese said.

The question people will be asked at the referendum on the Voice will be known by the end of June.

The final wording must be endorsed by both houses of Parliament before Australians cast their votes.

The Liberals have yet to come to a formal party position on the Voice, with shadow treasurer Angus Taylor indicating further talks were still to take place in the party room.

Labor senator Pat Dodson, the government’s special envoy for reconciliation, stressed the need to secure the Voice before a treaty.

“To have a treaty, you have to have a voice. You have to have an entity. You have to have a group of people that have a standing or that have credibility,” he said.

-AAP