With voters offside and crossbench senators showing no signs of complying with unpopular budget measures, some Liberals complained that the Treasurer's move had ''predictably'' brought the opposite effect, branding his threat to cut other spending ''unwise''.

They revealed Mr Hockey's move had not been part of the agreed government strategy for the day, which had been to press the opposition exclusively on the carbon tax repeal.

One senior figure asked why Mr Hockey had seen fit to open up another front. ''It was a gift to Labor … they did what you would do in that case and started picking us off, demanding that we say where the cuts will be. We would've done the same; it was an own goal,'' the frontbencher said.

Another long-time Liberal said the budget was in trouble because it lacked consistency, with the ''only unifying thing being how it has unified our enemies''.

The complaints came after Mr Hockey used a series of interviews on Wednesday to toughen the budget rhetoric. ''If the Senate chooses to block savings initiatives, then we need to look at other savings initiatives that may not require legislation,'' he said.

Opposition frontbenchers immediately capitalised on the threat, issuing multiple press releases on a portfolio by portfolio basis, challenging the government to expressly rule out further cuts to services such as health, education, social services and foreign aid.

''Australia's dedicated carers are already facing a real cut to their modest payments in this budget - with ongoing uncertainty and continued anxiety because of government's McClure review of the welfare system,'' opposition spokeswoman for carers and communities Claire Moore said in a statement typical of other areas. ''Joe Hockey needs to rule out cutting even more support from our carers.''

In question time Labor called on Prime Minister Tony Abbott to rule out adopting harsh aspects of its recent commission of audit report such as an even higher GP co-payment of $15 a visit, the calculation of the family home in the pension assets test, the scrapping altogether of family tax benefit (part B), and cuts to hospitals and schools.

Amid the concerns over ill-discipline and mixed messaging, new Liberal senator James McGrath has set out a radical libertarian program in his maiden speech, calling for the GST rate to rise to 15 per cent, federal health and education departments to be abolished and the ABC to be sold if it fails to address perceived left-wing bias.

But new Liberal Democratic senator David Leyonhjelm called on his colleagues to recognise the seriousness of the budget challenge and pass savings measures.

He said Mr Hockey's warning to Labor, the Greens and the crossbench about going around them was, in his view, clearly directed at the PUP. ''I think that he is signalling most strongly to the PUP senators that they are aiming to block all the savings but we have got a budget problem.''

SMH