The Liberal MP who quit the frontbench due to his stance on the Indigenous voice has urged his coalition colleagues to back the proposal.

Julian Leeser called for a respectful debate on the Indigenous voice and said the body was much needed to help fix a broken system.

Mr Leeser stepped down from his position as the coalition’s Indigenous Australians spokesman earlier this year after the Liberals decided not to back the voice to parliament and executive government.

Speaking before parliament, Mr Leeser moved to address concerns about the voice expressed by his coalition colleagues.

“The voice is advisory – it won’t be Moses handing down tablets from the mountain,” he said.

“The parliament will still be the democratic centre of our democratic life.”

Mr Leeser said the voice was not about “two classes of Australians”. 

“It’s actually about eliminating the differences in economic and social outcomes that separate Indigenous Australians from other Australians,” he said.

Mr Leeser said voting to enshrine the voice was in keeping with coalition values, and the body would make a difference in Indigenous policy areas.

“In most referendum debates, the argument is put that if it ain’t broke, don’t fix it,” he said.

“That’s normally a valid and compelling argument but the system is broken.

“Despite the small progress on some fronts, Indigenous Australians are not enjoying the same opportunities or outcomes as other Australians.”

Following another late-night sitting of parliament, lower house MPs will continue debating the final form of the Indigenous voice referendum on Thursday before the constitutional change is put to the public later this year.

On Wednesday, former prime minister Scott Morrison used a rare speech in parliament since his election loss to oppose the voice.

Mr Morrison said the proposed constitutional change represented an unknown risk.

“Permanently changing the constitution in the way the government proposes will sadly not change the desperate circumstances being experienced in so many Indigenous communities across Australia,” he said.

“The impact of the voice on the operations of executive government and the parliament are also not known, presenting significant and unknown risks that cannot be easily remedied.”

Mr Leeser urged advocates for both the ‘no’ and ‘yes’ votes to show each other respect during the debate.

“We can’t let this debate become yet another place of cultural fraying,” he said.

“For about two decades, our shared sense of belonging has been fraying.

“We are dealing with an amendment about our fellow citizens.

“We all have a responsibility to engage in this debate respectfully, and I might add, gently.”

The lower house isn’t expected to vote on the voice bill until next week when the debate will shift to the Senate.

The bill is expected to be finalised next month ahead of the referendum, which will be held between October and December.