Is it time for Labour to ditch Ed?

Miliband's so unpopular nothing he does seems to work out. Yesterday he tried to re-brand himself. Using the phrase 'cost of living' over and over again, nobody was convinced. He is only surpassed by Michael Foot at this stage in the electoral cycle in negative personal poll ratings. Is it time for Miliband to go? 

If there were more time, it would be an easy question to answer. If there were time for a new leader to properly establish themselves before everyone gets all tense, Labour would have to listen to the people. It isn't so clear cut now. A new leader may now only have an incredibly slim chance of electoral victory, but that isn't all the upcoming election will be about for Labour. 
North of the border, the SNP are making huge gains. South of the border, UKIP are. Labour seats are threatened. In fact, dozens of Labour safe seats are threatened. Labour could loose 40 seats in Scotland and god knows how many in England. Labour are fighting for their very survival as a serious political force. 
Who would Labour replace Miliband with? That's the hurdle. Miliband's inner circle have been severely under-utilised so far, which has undoubtedly hurt Labour's campaign. Yet it has helped Miliband retain control of the party- there aren't many high profile figures that can both unify the party and inspire the electorate. 
In Scotland, where Labour face an SNP shaped crisis, Labour could do with Jim Murphy or Gordon Brown. Murphy will probably be leader of the Scottish Labour Party soon, which will help somewhat, but it will take a UK wide leader to stop the landslide. And Gordon Brown wouldn't go down well with the English electorate. 
In the North of England, there isn't really any obvious alternative. 
Miliband could be dragging Labour towards catastrophe. But he can't be replaced now. Labour candidates and front benches need to work harder than they ever have before to stop Labour becoming an insignificant footnote in British politics.