By Ian Dunt
Alan Johnson has cemented his reputation as a potential problem for Ed Miliband with a public call for his leader to cut his ties with unions.
Mr Miliband beat his brother in the leadership contest by just 1.3%, mostly thanks to winning the union voting block. Many New Labour figures felt that union leaders had won it for their man following early meetings in which they agreed to back one candidate to fight off the more centrist David Miliband candidacy.
Even outside the New Labour tribe, many Labour supporters are concerned about the impression the voting system leaves, with some people allowed multiple votes. A union affiliated Cabinet-level MP, for instance, would have four votes.
"It can be 'one-member four votes' and that's wrong," Mr Johnson told the Times newspaper.
He was backed by former health secretary Alan Milburn and Margaret Hodge. Both are former Blairites, like Mr Johnson - a tribe Mr Miliband tried to pacify by inviting the former home secretary onto the front bench.
Many analysts expect a commission on party reform to be set up when Mr Miliband addresses the national policy forum next month.
But he is unlikely to be pleased by Mr Johnson's decision to issue a public demand about the policy. Any decision to change the rules is now likely to be seen as a capitulation to internal pressure.
The outburst cements the impression that relations between Mr Miliband and his shadow chancellor are less than perfect.
Mr Johnson spent much of last weekend openly discussing areas of difference between him and his leader, notably in the areas of a 50p top rate of tax and the funding of higher education - both issues on which he is well to the right of Mr Miliband.