Ed Balls
Ed Balls has warned of tough decisions aheadReuters

Ed Balls' final party conference speech before the general election had a single, overriding message: voters can trust a Labour government not to wreck the economy and stall the recovery.

And, just to prove the point, he confirmed he would continue to freeze child benefits, an announcement that was met with a distinctly chilly silence from the conference floor. He won't have minded that.

The fact that the measure will save only a relatively paltry £400m or less, that it overturns previous reluctance to follow the Tory policy and that child benefit is close to Labour's ideological heart indicates what this is really about.

It is supposed to send out a powerful signal that the party is ready to take particularly difficult, unpopular polices to balance the books.

To the same end, it was a speech with no big rabbit pulled from the shadow chancellor's hat but which was heavy on re-announcing a whole series of known policies – from reintroducing the 10p tax rate to scrapping the bedroom tax.

As Balls told the party faithful in Manchester: "I cannot make promises I cannot pay for. There are going to be some difficult decisions.

"The next Labour government will get the deficit down. Ed Miliband and all my shadow cabinet colleagues are clear it will mean cuts and tough decisions and we will take the lead.

"Labour will balance the books in the next parliament. These will be our tough fiscal rules. We will get the current budget into surplus and the national debt falling as soon as possible in the next parliament.".

But the real problem for Labour is the messenger, rather than the message.

Whatever Balls' economic credentials, the Tory slogan about not giving the keys back to the driver who crashed the car has stuck to him and he has found it impossible to dislodge it.

The most startling evidence for that was the latest poll showing the Tories 25 points ahead of Labour on the economy.

There are many in the Labour party who believe that in the post-2010 election trauma, the party failed to hit back hard enough at the Tory campaign to lay the entire blame for the recession at Balls' and Gordon Brown's door.

Other powerful voices inside the shadow cabinet were actually pressing hard for Miliband and Balls to throw their hands up, accept they messed up and take responsibility in the hope that would somehow clear the decks.

The upshot of that split was half-hearted apologies about not regulating the financial sector more and equally half-hearted claims spending had not been too high under the last Labour government.

Child benefit
Labour will continue to freeze child benefitReuters

And again, Balls told the conference: "Where we made mistakes, like all governments do, we should be grown up about it.

"We should put our hands up, learn from the past and explain how we will do things differently in the future.

"We should have regulated those banks in a tougher way. It was a mistake. We should apologise for it. And I do."

Balls did attempt to turn the heat on to the chancellor in his speech, saying: "Three years of lost growth at the start of this parliament means we will have to deal with a deficit of £75bn, not the balanced budget George Osborne promised by 2015. And that will make the task of governing hugely difficult."

It is a powerful line of attack. But the fact is, the Tory line about crashing the car has now embedded itself into voters' minds and it is probably too late to dislodge it, even with more half-hearted apologies.

So the best Balls can do is show he is not about pulling expensive rabbits out of his hat but is careful, responsible and, above all else, fair.

And that remains his strongest card. By balancing the child benefit freeze against increasing the top rate of tax, for one example, Balls wants to drive home the message about the government standing up for the wrong people.

Only a Labour government, he insisted, would deliver policies for the whole country. And his entire speech amounted to a single slogan: "Trust Me".