Miliband cuts stance - masterstroke or own goal?
It's a well-worn political path. Labour leaders in opposition seek to gain traction not simply by attacking the government but by criticising their "own" side.
Neil Kinnock called time on the ultra-left Militant Tendency, attacking the Trotskyist-led Liverpool council, and helped burnish his own credentials as a passionate moderniser.
John Smith imposed "one member, one vote" elections on - largely surly- trade union leaders.
And Tony Blair was, of course, the master - annoying the left by ditching Clause Four, but proving he was changing Labour in the process.
Ed Miliband initially adopted a different tack but - slipping in the polls - clearly calculated that, in this new year, he would try a new approach.
So he didn't limit his message to a refusal to reverse coalition cuts, he also endorsed a freeze on public sector pay.
Some strategists see this is a masterstroke.
If Labour aren't in office, they can't influence the level of public sector pay anyway.
But - behind the Conservatives in the polls on the question of economic competence - Mr Miliband can at least signal that he recognises harsh financial realities and reassure those in the private sector who are facing a squeeze on incomes that he isn't showing favouritism to public sector workers.
Simultaneously, he can demonstrate he isn't in the pockets of the very trade unions which were so crucial to his narrow victory as Labour leader.
So far, so good.
Having a spurious row with the unions rarely harms a Labour leader's standing with the wider public. But this dispute shows signs of turning serious. Some insiders are now questioning whether enough groundwork had been done before the policy shift was announced.
So Mr Miliband has quickly encountered three problems - none of which are an attack from the coalition.
Turning the knife
First, the relatively moderate GMB union, which funds Labour to the tune of more than a million pounds a year, was clearly not onside in advance - and their general secretary is now contemplating cutting financial support.
Second, Unite's Len McCLuskey has chosen to play the man as well as the ball.
In his Guardian article, he doesn't just attack Mr Miliband's policy. He attacks his leadership.
In this, he knows what he is doing - not just sticking in the knife, but turning it.
Ed Miliband addressed a meeting of his parliamentary party last night and received very vocal support from some of those who were present.
But some of those who kept their own counsel at the meeting told me afterwards that they hadn't been impressed with their leader's presentation - and feared the party would not win if he remained in place.
They weren't imparting news of a plot or suggesting there would, or should, be a leadership challenge.
Instead, they were expressing frustration which has been simmering because Labour isn't pulling ahead consistently in the polls.
That brings us to problem number three.
Few MPs express concerns about Mr Miliband publicly because they correctly calculate, in the absence of any realistic or likely alternative, there is not much to be gained by wounding him.
But the backbencher John Mann did go public today.
He doesn't agree with the pay freeze policy but his overarching point is more important and is shared silently by some of his colleagues.
He believes it isn't good enough for the party leader simply to refuse to commit himself to reversing cuts.
Instead, Mr Miliband has to set out a wider vision.
Mr Man says he needs to put "flesh on the bones" of his policy and say more clearly where Labour would save money, and, equally, what services it would defend.
Some MPs simply scoffed at their leader's assertion last night that he was winning the battle of ideas.
That said, the atmosphere among Ed Miliband's advisers is positive - they feel he has effected a significant shift in Labour's position and that he is getting his message across.
They face a row today but take the view that the one thing that is worse than being talked about is not being talked about.
They feel their leader is now making an impact.