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
Tony Davies was the first civilian to reach Pc Palmer after he was stabbed during the Westminster attack.
Defiant Londoners put on a show of solidarity for the victims of the Westminster terror attack at a vigil in their honour.
Weather set to improve with plenty of sunshine by Saturday