They have warned Australia's offshore immigration centres will again become "living graveyards" if the federal government succeeds in reversing the medevac legislation.

The 51,000-strong petition was presented to a cross-party group made up of Labor, the Greens and independent MP Andrew Wilkie who said offshore detention without medical care was "murder".

"The blood of many asylum seekers are on the hands of many politicians," he said.

The Asylum Seeker Resource Centre is pleading with independent senator Jacqui Lambie to use her casting vote to keep it in place.

The Morrison government hopes to win her support to repeal the law, passed against its wishes in February, that makes it easier to bring refugees to Australia for medical treatment.

Polling released on Tuesday found three in five people think the laws either don't go far enough to provide humane treatment or strike the right balance.

This is significantly higher than in February, the analysis from Essential Research says.

ASRC head Kon Karapanagiotidis says that contrary to the scary picture the government painted when the law passed, there haven't been hordes of people coming to Australia overnight, the asylum boats haven't restarted and there hasn't been a single national security incident.

"What we have seen through medevac have been men who had kidney stones so serious that they would have actually died if not transferred have been saved," he told AAP on Tuesday.

"A man who would have lost a limb after being violently attacked in Manus Island had that limb saved."

He's appealing to Senator Lambie's compassion on the issue.

The nation was now at a crossroads, he said, recalling his visit to the Manus Island immigration centre two years ago.

"What we saw was a medical catastrophe, like a living graveyard," he said.

"Why would we go back to what we had before?"

Labor immigration spokesperson Kristina Keneally said the government was portraying itself as powerless to repeal medevac decisions, but that wasn't the case.

As of last Thursday, government figures show 169 people have been brought to Australia from offshore centres under the medevac law.

Analysis by the ASRC finds 86 per cent of transfers were approved by Home Affairs Minister Peter Dutton without reference to an independent medical panel.

Senator Lambie has indicated she wants to land a deal that amends the system, without giving the government a full repeal.

The issue is scheduled for debate in the Senate on Wednesday.

Australian Associated Press