While the bill applies a narrow definition of security in its current form, the Labor changes would ensure paedophiles, rapists and other criminals could be rejected, answering one of the government’s criticisms of the bill. Loading A second change would give the minister more time to respond to the recommendation of a medical panel on each transfer, increasing the timeframe from 24 hours in the current bill. This responds to another criticism from the government, that the Immigration Minister would not have enough time to check the history of an applicant if every transfer had to be finalised within 24 hours. A third amendment is to apply the medical transfer bill to the existing cohort of refugees on Manus Island and Nauru, where about 1000 people have waited for years to be transferred to third countries.

This amendment follows warnings from Immigration Minister David Coleman that the bill in its current form could allow all asylum seekers coming by boat to apply for urgent medical help in Australia as soon as they arrived, without going to the offshore detention centres. Mr Shorten has cleared the three principles with shadow cabinet and gained approval from the Labor caucus on Monday night to negotiate on these terms with crossbench MPs ahead of a vote on on Tuesday afternoon. Two senior members of the Left faction, Pat Conroy and Andrew Giles, spoke in support of the changes in the caucus meeting, with no other MPs speaking after the Labor immigration spokesman, Shayne Neumann, outlined the changes. Mr Giles told the meeting the Labor principles did not change the principles of the Senate amendments. Mr Giles also emphasised the need to get the bill through the Parliament this week.

Mr Conroy suggested that any significant changes to the principles, such as any agreement Mr Neumann made with crossbench MPs, should go back to a caucus committee for approval to ensure caucus had the final say. This was backed by the meeting but does not mean a full caucus meeting would be required. Loading But Greens MP Adam Bandt has rebuked Labor for putting forward the changes rather than passing the medical transfer bill in full. "I am angry that Labor is once again caving in when it comes to refugees," Mr Bandt said. Labor could need his vote to secure the changes in Parliament. Mr Morrison said there was no need to change existing law because it already allowed for medical transfers with the full discretion of the minister to make the final decision.

"This bill is unnecessary, it is superfluous, it adds nothing to border protection – it only takes away," the Prime Minister told the National Press Club. "And therefore its passage in any form takes us backwards. You don’t need this bill to make sure Australia has control of its borders. We already do. "I’m not going to find some middle ground. You can’t split the difference on 1,200 deaths," he said, referring to the estimate of deaths at sea from asylum seeker boats in recent years. Some crossbench MPs are said to be "receptive" to the Labor proposals but negotiations are set to continue until Tuesday, when Parliament resumes on its first sitting day for the year. The combined effect of the changes is to strengthen the discretion of the minister in terms of the grounds for refusal and the time needed for a decision, without weakening the right of doctors to recommend a transfer on medical grounds for those who raise no security concerns.

The bill will go to the House as a "message from the Senate" on Tuesday and is expected to come up between noon and Question Time at 2pm, but any vote would have to wait until after matters of public importance are debated after Question Time. Loading The supporters of the bill will not need an absolute majority – that is, 76 of the 150 members of the lower house – to win the debate. Labor has 69 members and is negotiating support for its changes from Mr Bandt and independents Julia Banks, Cathy McGowan, Kerryn Phelps, Rebekha Sharkie and Andrew Wilkie. This bloc of 75 would be enough to pass the bill and make it law over the government’s objections.