Wyatt, the first Indigenous person to hold the portfolio, resigned his membership on Thursday after Liberal leader Peter Dutton on Wednesday said the party would oppose the voice to parliament.

The party said that backbenchers were free to support the voice but frontbenchers were now locked in to opposing bi-partisan support for the move, which will be voted on at a national referendum later this year.

“I still believe in the Liberal Party values but I don’t believe in what the Liberals have become,” Wyatt told the West Australian newspaper.

“Aboriginal people are reaching out to be heard but the Liberals have rejected their invitation.”

Wyatt was a member of the referendum working group which helped shape the final proposal being put to the public at the poll later this year.

He was also a member of cabinet in Scott Morrison’s government when a previous version of the Indigenous voice was being considered, serving as a minister from 2019 to 2022 before losing his WA-based seat at the last federal election.

Liberal MP Bridget Archer has also considered resigning over the party’s position.

“Sometimes I do consider (resigning) and then I consider the people in the Liberal Party that share my views … people that I consider to be like-minded Liberals,” she said on Thursday.

“I stay because I know that I am not the only person that thinks that way and I stay because I think the Liberal Party is at a crossroads.”

Archer said it was another example of the Liberal Party not presenting a credible alternative to government in opposition.

She said she was concerned about Opposition Leader Peter Dutton confirming he would actively support a ‘no’ campaign on the voice.

“We’ve already seen warnings from the Racial Discrimination Commissioner about the rhetoric that we’re seeing from a ‘no’ campaign,” she said.

“It is going to be an unpleasant and divisive road ahead if that continues … and we should be seeking to not even want to be adjacent to that sort of language and that sort of posturing.”

Former Liberal leader John Hewson said Dutton had failed to learn any lessons from the party’s recent historic loss at the Aston by-election in Melbourne – the first time an Opposition had lost a seat to the government in a by-election for 123 years.

“One of the messages of Aston was that people are sick and tired of politicians playing games, just scoring points on each other on the negativity of the opposition,” Hewson said said.

Former deputy Liberal leader and Aboriginal affairs minister Fred Chaney said the decision to oppose the voice was a “massive disappointment”.

“I’m sadly not surprised because I think they’re desperately looking for political advantage on this, instead of treating it as a serious issue and I think it’s a big sell-out of their own legacy,” he said.

“They are playing politics with this, I think they’ve been doing that for months now. This whole question about more detail has been a cover for the desire to oppose it.”

-with AAP