Australians aren't ready to vote for the proposal on an Indigenous Voice, the opposition leader says, despite his party supporting legislation enabling a referendum to be held.
In supporting the legislation in parliament this week, Peter Dutton said the opposition did not want to get in the way of a democratic process committed to by the government.
He also believed the question of constitutional recognition was important to ask Australians, but unanswered details from the government were putting the debate in a precarious position.
"At the moment, the country is not ready to vote for the voice as the government is proposing," he told ABC Radio.
"The proposal of the voice goes beyond, I believe, where the Australian public is."
But Education Minister Jason Clare said the opposition did not collaborate with the government while the proposal was going through parliament.
"Peter Dutton has not offered one single idea here," he told Seven's Sunrise.
"The legislation has gone through the parliament, the Liberal Party who are now saying they've got concerns with this did not offer one single amendment.
"So this shows that the Liberal Party aren't fair dinkum."
The prime minister is working with advisers on setting a date for the referendum, but there has been speculation that October 14 is the government's preferred date.