Facing a revolt: Greens leader Christine Milne. Credit:Penny Bradfield If Labor and the Greens block the deficit tax, Mr Abbott would fail to get the legislation through either the current or the new Senate, which will be dominated by Clive Palmer's senators, who are likely to oppose any tax increases. Mr Abbott's deficit tax appeared destined to fail earlier this week when Senator Milne said: "This is totally the wrong way to go and it's no wonder the Liberal cabinet is in chaos with Tony's tax." But a Greens source said Senator Milne had angered colleagues by shunning Mr Abbott's unlikely embrace of progressive taxation. Another senior Greens source acknowledged that constituents had been complaining about the party leader's position. "Senator Milne's been out since day one saying she doesn't support [the tax], despite the fact it is Greens party policy," a source said.

Illustration: Matt Golding. "Her response hasn't gone down well with a number of key people in the party and the membership. "She's now trying to work out what to do as she is set to be rolled in party room on it." Asked about the internal anger, Greens senator Lee Rhiannon replied: “While I support robust debate in the party room, I don’t support leaking internal policy debates to the media and having the debate in public.” Leaked emails reveal Greens voters have been complaining to Senator Milne's office, suggesting she was betraying her constituents by opposing tax increases on wealthy people.

One frustrated voter asked Senator Milne: "How can the Greens leadership/parliamentarians oppose a 1 per cent levy on people earning $150k per annum? "I am extremely doubtful that your grass roots members, like me, would oppose such a levy." The constituent's claim is supported by polling data – a Fairfax Media-ReachTEL poll of 3241 people taken last week showed more than half of Greens voters supported Mr Abbott's debt tax. Senator Milne's adviser told the constituent that while Greens MPs supported the "general proposition" of progressive taxation, they would not support Mr Abbott's debt tax because it did not "constitute tax reform". Senator Milne was on personal leave when contacted, but on Saturday acting Greens leader Adam Bandt used noticeably softer rhetoric, suggesting the party may support Mr Abbott's debt tax after all.

“The Greens don't accept Joe Hockey's confected 'budget emergency' argument, which he is tying this mooted temporary deficit levy to," Mr Bandt said. "Equally, we have long argued for a more progressive taxation system and more permanent tax reform in Australia. "There have now been so many rumours about what the government intends to do that we will wait and see what emerges on budget night before deciding on a final position.”