The West Australian Nationals have withdrawn their support for an Indigenous voice to parliament, claiming Labor's model is flawed.
It brings their position into line with the federal party's stance, after the WA branch previously indicated support for a constitutionally enshrined voice.
In 2019, the WA Nationals backed the intent of the Uluru Statement of the Heart.
However on Saturday, WA opposition leader Shane Love said the federal Labor government needed to give more details on how the voice would function.
He said if it were a straightforward question of constitutional recognition the party would support it, but he was not satisfied with Labor's proposal.
"It was determined that we did not support that, we did not trust the Labor government to be able to deliver on the voice," the WA Nationals party leader told reporters.
"There was a diversity of views in the room, it's not a matter of the party making some sort of shallow bid to make an electoral advantage."
He said the party believed in empowering elders at a local level and funding grassroots programs to address closing the gap.
Mr Love added that MPs would be permitted to campaign on the referendum as they saw fit.
The decision was made at the WA Nationals' annual state conference held in the Swan Valley near Perth.
Prime Minister Anthony Albanese is set to reveal the date of the referendum in Adelaide on Wednesday, with the vote widely tipped to be held on October 14.
The WA Nationals' stance comes after controversy surrounding Aboriginal cultural heritage laws, which the state Labor government has since scrapped.
WA Liberal leader Libby Mettam also withdrew her support for the 'yes' campaign earlier in August.