A new biography reveals that Treasurer Joe Hockey wanted a much tougher budget, but was convinced by Prime Minister Tony Abbott to take a more cautious approach.

The book alleges that the treasurer wanted the deficit levy applied to more taxpayers, and cuts to entitlements for older Australians, according to a Fairfax report.

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Surprisingly, Mr Hockey has also been labelled as Mr Abbott’s most likely successor, with the Prime Minister’s chief of staff, Peta Credlin, saying that Mr Hockey has “got his head above every other contender”.

The new allegations are contained in Hockey: Not Your Average Joe, which was written by journalist Madonna King.

Ms King had the co-operation of Mr Hockey, former Prime Minister John Howard and former Treasurer Peter Costello when writing the book.

The book has also revealed the treasurer’s unlikely friends and enemies, with tensions between Mr Hockey and Industry Minister Ian Macfarlane over the government’s tough stance on industry assistance for Holden.

Ms King says that the treasurer has found a friend in former former Labor prime minister Bob Hawke.