The ban on the ACT and Northern Territory being able to legalise assisted suicide could be lifted after a looming Senate showdown on euthanasia.
Liberal Democrats senator David Leyonhjelm's private bill repealing the 1997 ban on territories controlling euthanasia laws will be debated when parliament resumes after the winter break in August.
He said he had a personal guarantee from Prime Minister Malcolm Turnbull the Liberal Party would be allowed a free vote on the bill, which the government will allow to proceed to the lower house.
"As a Liberal Democrat I believe in the right of individuals to end their lives painlessly at a time of their choosing, as do the majority of Australians," Senator Leyonhjelm said.
Senator Leyonhjelm, with the support of Labor, the Greens and crossbenchers including Pauline Hanson, Derryn Hinch, Brian Burston and Tim Storer, passed a motion on Wednesday to deal with the bill on August 14.
Senator Leyonhjelm's legislation will take priority until it is voted on.
But the issue is likely to spark a conservative backlash in the coalition, fresh from last year's divisions over same-sex marriage.
Senator Leyonhjelm has confirmed his support for reviving the Australian Building and Construction Commission was traded for the government allowing the bill to be debated.
Former prime minister Tony Abbott is worried the "secret deal" with Senator Leyonhjelm wasn't put to the partyroom by Mr Turnbull.
"The prime minister likes to talk about due process, I'm very concerned about lack of due process," Mr Abbott told 2GB.
Tasmanian conservative Eric Abetz said parliament permitting and promoting suicide in any circumstance diminished the value of human life.
"I trust news reports that the government traded the issue of state-promoted suicide in exchange for support of other legislation in Senate negotiations is incorrect," Senator Abetz said.
Katter's Australia Party senator Fraser Anning said assisted suicide was a direct attack on the sanctity of life, arguing the ACT's "socialist" government would legalise euthanasia.
The NT legalised euthanasia in 1995 and it came into effect in 1996.
But by 1997 the law was nullified when the federal government amended the territory's self-government act.
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Australian Associated Press