Speaking to ITV News, David Blunkett has told those criticising Ed Miliband to "get off your bum, and get out there and campaign."
The veteran MP - who has announced he is standing down - said: "My message to people who are chipping away at Ed Miliband: forget the idea that someone else is going to step forward or there's going to be some kind of peremptory election. There isn't.
"So get off your bum and get out there and campaign. Not for any individual but for the values we espouse."
Mr Blunkett added that if Labour were to lose next year's election they could be out of power for a very long time.
More top news
David Cameron will say the Tories are the party of the "grafters, roofers, retailers and plumbers" as he set out plans to help small firms
Lib Dem leader Nick Clegg will say his party are fighting '60 Eastleighs' on the campaign trail in the Hampshire constituency today.
The late Coronation Street actress Anne Kirkbride has been nominated for a British Soap Award.