Not just to keep Labour MPs in line, but to broaden the current crisis engulfing Labour into something cross-party, when it clearly isn't. From the Telegraph:
"Don't please, through your actions, make it any worse for the Labour Party than for the other parties who have all got to come to grips with this crisis affecting British politics."
Obviously he's talking about expenses. The problem, however, is that all the polls - with the exception of a rather fruity ComRes - have said that the Tories are actually doing okay on this issue - largely thanks to Cameron's leadership.
And the other, wider, problem is that this isn't really about expenses at all. It's about Labour picking the wrong man as their leader; it's about that man quite possibly being the worst Prime Minister in history; and it's about the public coming to realise that this government - whoever leads it - is morally, intellectually and politically bankrupt.