Senators have been urged to scrap "undemocratic" laws blocking Australian territories from legalising voluntary euthanasia.
Legislation passed by the federal parliament two decades ago banned the ACT and Northern Territory from passing their own assisted dying laws.
The chief ministers of the territories have taken out a full-page advertisement in The Australian calling on the Senate to restore the rights of their residents to decide on their laws.
"Voting for this bill doesn't mean there will be assisted dying in the NT or the ACT," Andrew Barr and Michael Gunner wrote.
"It will simply give territorians the same right to decide on it as other Australians."
Pressure is mounting on the prime minister to allow votes on the bill in both houses of parliament.
Senator David Leyonhjelm says he was guaranteed a vote in both chambers in return for his support for re-establishing the Australian Building and Construction Commission.
The prime minister has since denied agreeing to the deal.
Senator Leyonhjelm, who insists staff witnessed the deal being done, is threatening to vote against the National Energy Guarantee if it is not upheld.
"If the government insists on denying the deal I had with the prime minister to bring my bill to the house if it passes the Senate, I'm going to be very hard to persuade on anything on the NEG," he told reporters in Canberra.
Mathias Cormann, the leader of the government in the Senate, said he was not part of any conversations in which such a commitment was made.
"The prime minister himself has also denied that such a commitment was made," Senator Cormann told ABC radio.
The upper house will start debating the bill restoring territory rights on euthanasia on Tuesday.
Senator Leyonhjelm believes there is enough Senate support to repeal the 1997 legislation.
Whether or not the prime minister allows debate in the lower house is another matter.
Senator Leyonhjelm's implied threat carries weight because the coalition needs the backing of eight-of-the 10 crossbench senators to pass legislation that Labor and the Greens don't support.
Right To Life president Margaret Tighe said using the guise of territory rights showed blatant disregard for the welfare of indigenous people in the NT who lack access to palliative care.
"Would those same senators who claim to be more concerned about so-called territory rights be willing to give rights to the territories to legalise capital punishment?" Ms Tighe said in a statement.