The Greens leader, Christine Milne, has indicated she could back an immediate shift to a floating carbon price as speculation mounts the Palmer United party (PUP) is preparing to announce it will support some elements of the existing carbon pricing scheme.



Sources close to Milne said she is seriously considering an earlier move to flexible pricing to try to avoid the carbon price being repealed.



According to the sources, Milne’s current thinking is that what she calls Tony Abbott’s “denialist” climate policy means that a much lower flexible carbon price would be preferable to nothing at all and might be more attractive to the new Senate.



Clive Palmer – who had always supported the carbon tax repeal – will announce his party’s final position on the issue on Wednesday night.



Guardian Australia understands Palmer and the former US vice-president Al Gore are meeting and that it is possible, although not confirmed, that Gore could attend Palmer's media conference.



Sources said Palmer was preparing to back some elements of the existing package. His party may vote against the abolition of the Clean Energy Finance Corporation (CEFC) and the independent Climate Change Authority and could possibly back some delay in the repeal of the carbon price itself while other policy options are considered. The PUP is also considering its position on the renewable energy target (RET), which the government is reviewing.



Palmer and his three senators-elect are meeting to finalise their position on the carbon tax repeal and other key pieces of legislation before the announcement.



The PUP leader told the ABC his announcement would have international significance.



"Wednesday night we'll have an announcement to make on what we think is a solution for Australia and the world," he said, predicting it would be a "big day, massive day".



The Green sources said the possibility Palmer was considering some shift in his previous clear position in favour of repeal had crystallised Milne’s thinking on bringing forward a floating price, because it meant there was some chance it could succeed.



Under existing law the fixed carbon price is set to rise to $25.40 next week. A floating price would mirror the international price which is about $8.



Under the existing law the carbon price would move to a floating price in July 2015. If the PUP did make the extraordinary shift of backing a quicker move to a floating price it would pass the Senate with the backing of the Greens and Labor – who took the same policy to the last election.



It is highly unlikely to be accepted by the government, setting up a showdown on the central policy debate of the 2013 election.



Also complicating the picture is the position of the independent senator Nick Xenophon, who told Guardian Australia this week he wanted a vote on the carbon repeal delayed until the government provided more information about its alternative Direct Action scheme. Also, the Motoring Enthusiast senator, Ricky Muir, has signed a memorandum of understanding with the PUP, but has also indicated he will vote independently on some issues. Muir’s advisers have also indicated he could support the retention of the CEFC, which is also backed by Xenophon and the DLP senator John Madigan.



Palmer is scheduled to meet Tony Abbott on Thursday morning.