The real reason for the Greens' breakup with Labor is to save two of their sitting members, a government backbencher says.
The minor party on Tuesday effectively ended the agreement that has kept the federal government in power in a hung parliament for more than two years.
But it will still guarantee supply and confidence.
"I think someone had failed to install an energy efficient globe somewhere and they decided that that was the end of the deal," he told Sky News on Wednesday.
"This is about them just trying to find a way to save two of their members that are in very tough fights, in Adam Bandt and Sarah Hanson-Young."
Mr Bandt, the Greens' only lower house representative, conceded he was in for a "tough fight" to win his seat again, but said he wanted to claim outright victory without relying on preferences.
He said it was his party, not Labor, that deserved credit for introducing a carbon price and taking steps to combat climate change.
"Labor went to the last election promising a citizens' assembly, and the coalition went promising nothing at all," the Melbourne MP told ABC radio on Wednesday.
"But in reality this is going to mean very little because the Greens are still going to keep the government on life support," he told Sky News.
Senator Milne on Wednesday said that now she had gone public with the agreement's breakdown, the Greens would be able to "very clearly" prosecute their case for getting more money out of the mining companies.
"It (the relationship) is a sham and there is no point in continuing a sham," she told Sky News.
Meanwhile, the Australian Christian Lobby says it never wants to see another alliance between the Greens and a mainstream political party.
Managing director Jim Wallace says the Greens are to the left of politics what One Nation was to the right.