Last week Gillard had won a fragile victory over the left in a caucus debate that put Labor's survival ahead of deep misgivings over legislation drafted to hand the immigration minister power to implement policies regarded as the best option for dealing with asylum seekers.
The proposed amendments to the Migration Act would not only allow the Government to go ahead with its plan to exchange 800 asylum seekers for 4000 United Nations-accredited refugees from Malaysia, but also open to way for future changes by a Coalition government.
But key figures of the Labor left yesterday rejected the plan after seeing the details, and Abbott attacked the amendments in Parliament after a 15-minute meeting with Gillard.
Abbott said the latest draft paid only lip service to the required human rights protections demanded by the UN Refugee Convention and he would now take his own set of amendments to the party room.
The Opposition rejects the Malaysian deal and wants Nauru reopened.
Under the new draft amendments the immigration minister would be required to consider the national interest in any policy on asylum seekers, and to consider whether a country to which they might be sent met the principal obligations of the UN Refugee Convention.
This meant that people should not be returned to a place where they would face persecution, Gillard said.
She said the issue was too important to be treated as "politics as usual" and that Australians wanted a solution in the national interest.
"I'm resolved that we are able, as a nation, to still have offshore processing," she said.
But without Abbott's support the law is doomed.
The Greens, who control the balance of power in the Senate, yesterday repeated their determination to vote the legislation down.
Immigration spokeswoman Sarah Hanson-Young said the debate had become "an auction on who can be the meanest, the nastiest and the cruellest", and leader Bob Brown described the proposed legislation as an "onslaught against simple humanity and the rule of law".