When Brown became PM he promised a change from the Spin, hype and PR manipulation that Blair was so adept at. Unfortunately, we had become so used to the spin, that when it went away and we were presented with the truth, it appeared like the government had come off the rails.
With Blair dragging his feet about leaving, a war of the Blairites and Brownites broke out in the Labour Party. Brown inherited a fractured party, and the cracks have just got bigger.
There is nothing he could have gone about the world economic situation, and the voters know that, but his failure (if it ever was possible) to re-unite the Party, and a Party apparently in a mood to self-destruct, is not appealing to the voters.
Can he survive? I don't think there is a better candidate at the moment. The Cabinet is populated with non entities, but it wouldn't be the first time a Labour Government has descended into a mess.