The move has been welcomed by proponents of the Voice, who are now hoping more like-minded Liberals will come out in support, but "no" proponents insist this is not a setback in their campaign.

Mr Leeser's decision comes as deputy opposition leader Sussan Ley launches a pre-budget, 16-electorate blitz in a bid to win over voters in seats lost in last year's federal election.

Opposition Leader Peter Dutton has stood firm on his party's decision to oppose the Indigenous Voice to Parliament, stating he was "very happy" with the Liberals' position, which "represents the overwhelming view" of the party room.

Mr Dutton described Mr Leeser, who was his shadow attorney-general, as a "great advocate" for Indigenous communities and a man of "great character".

"He has gone through a process in our party and his position is at odds with the overwhelming majority of the Liberal Party members in our party room," Mr Dutton said.

The Liberal party has denounced the Voice as divisive and has questioned whether it will provide practical outcomes for Indigenous Australians. The decision is binding for the Liberal frontbench but allows backbenchers to decide their own position.

In a move that could potentially embolden more Liberal MPs to reject the party decision, Mr Leeser said he would be moving to the backbench as he intends to campaign for the "yes" vote.

He told reporters he has "had many respectful discussions with colleagues about the Voice over the past year" but "hadn't been able to persuade them".

Mr Leeser said he remains loyal to his party and to Mr Dutton and his decision was "about keeping faith with an issue that I have been working on for almost a decade".

"I think what I want to be able to say to my children in the future, is that your father stood up for something that he believes in," he said.

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Mr Leeser will be joining Liberal backbencher Bridget Archer, who has been outspoken in her support for an Indigenous Voice. Other high-profile Liberal supporters for a Voice include Tasmanian Premier Jeremy Rockliff and former NSW premier Dominic Perrottet.

Morrison government Indigenous Affairs Minister Ken Wyatt quit the Liberals over its opposition to the Voice, last week.

However, leading "no" campaigner and former Liberal MP Warren Mundine told The Canberra Times Mr Leeser's resignation was "not one bit" a setback for the "no" campaign.

Mr Mundine said he was not surprised by Mr Leeser's decision and he always counted him as among those in the "yes" corner.

He said Mr Leeser was in a "small group" and the "no" campaign was "feeling very confident and very strong".

Meanwhile, Ms Ley's tour will target seats lost to Labor and the teal independents in 2022 as well as Liberal-held seats that the party must hold on to. The teal inner-city seats, including Warringah, North Sydney and Goldstein, must be won back for the Coalition to have any chance of forming government again.

Ms Ley has been steering the Liberal's teal fightback strategy, which includes rising cost-of-living issues, however it is noted in polling that in such inner-city seats the Voice emerges as a popular proposal.

Senior Labor MPs welcomed Mr Leeser's decision, but acting Prime Minister Penny Wong said she expects more Liberals to break ranks and follow Mr Leeser to the backbench.

"I suspect these Liberals will not be the last to break from Mr Dutton's partisan narrow position," Senator Wong said.

Minister for Indigenous Australians Linda Burney echoed Senator Wong's comments, stating Mr Leeser "knows how much work has gone in to getting Australia this far on the journey to reconciliation".