The Greens won't support Labor's three amendments to a bill to give doctors more say in whether asylum seekers are transferred to Australia for medical treatment.
Labor's proposed changes to a bill to make it easier to transfer critically-ill asylum seekers to Australia appear doomed after Greens leader Richard Di Natale declared his party would not support them.
The bill giving doctors more say on asylum seekers getting medical treatment in Australia passed the Senate in December with Labor's support, but under pressure from the government, the party wants to make last-minute changes.
Senator Di Natale said his party can't support the proposed amendments, including giving the minister power to reject a medical transfer on character grounds.
"The amendments put forward by the Labor Party may make the situation worse than doing nothing," Senator Di Natale told reporters on Tuesday.
The changes will not pass without the Greens support.
Earlier, independent MP Kerryn Phelps said she was determined to salvage the bill.
"I’m determined for us to find a pathway through, there are lives at stake here," Dr Phelps told reporters Tuesday morning.
But Labor's proposal to extend ministerial powers to block transfers of asylum seekers with a criminal record is shaping up as a "sticking point".
"That could take us right back to where we are today and that’s just not acceptable."
Prime Minister Scott Morrison said the bill remained unacceptable.
"I will not give a leave pass to this parliament to weaken our border security," Mr Morrison said outside an ecumenical church service marking the opening of parliament for the year on Tuesday.
Opposition Leader Bill Shorten said it was possible for Australia to have strong borders and treat refugees humanely.
"The current government confuses stubbornness with strength," he told reporters outside the same Canberra church.
"What I've done is listened to the border experts and listened to the refugee advocates.
"I think this is not an issue which should be dividing the nation."
'Fear is all he has left'
Labor Senator Penny Wong accused the prime minister of resorting to fearmongering in the face of an embarrassing defeat.
"Fear is all he has left. He can't run on his record because his record is cuts and chaos. He can't run on stability because they are so bitterly divided.
"So what does he want to run on? He wants to run on a fear campaign."
Finance Minister Mathias Cormann said Labor's change amounted to an admission they had got it wrong when they backed the bill in the Senate.
"If we as a government hadn't done everything we could to stop Bill Shorten from watering down our border protection arrangements towards the end of last year, a bill would now be law that - by Bill Shorten's own admission - would've prevented the government from turning away criminals from coming to Australia," Minister Cormann said.
Talks with crossbench continue
Labor is locked in discussions with the crossbench to get their support for amendments to the bill.
Dr Phelps said she would consult with lawyers and refugee advocates on Tuesday before a vote in Parliament as soon as this afternoon.
Independent MP Cathy McGowan said she will support the bill and amendments after discussions with Labor and her crossbench colleagues.