Ed Miliband is leading Labour to defeat at the hands of the Conservatives and has proved a worse leader than Neil Kinnock, former Cabinet minister Charles Clarke has said.
Blairite Mr Clarke said that Miliband had failed to produce an "overall story" to explain to voters why they would be better off with Labour in government.
Speaking to the Huffington Post, the former home secretary said Mr Miliband and shadow chancellor Ed Balls were wrong to reject claims that Labour overspent in office and said they had failed to "set out very clearly their own plan for controlling the deficit".
And he attacked the Labour leader and shadow home secretary Yvette Cooper for "ignorant and ill-informed" apologies for Labour's handling of immigration, insisting that the party was right to open the doors to workers from eastern Europe in the 2000s.
Mr Clarke rejected suggestions that personality issues will prevent Mr Miliband becoming prime minister. Asked if the Labour leader passed the test that voters could imagine him at 10 Downing Street, he said: "He does actually. I think he has a problem with the population, undoubtedly.. he is an intelligent man, he'd be a good prime minister. I don't myself think he's geeky."
But comparing him with Lord Kinnock, who took Labour to defeat in 1987 and 1992, he said: "Neil has far, far more qualities than Ed Miliband as a leader. Neil was a fantastic leader and brought Labour back towards victory."
And he said the " most likely outcome" of next year's general election was an overall majority for the Conservatives. Asked whether Labour could convince voters of its economic credibility in time for the May 7 poll, he replied: "I don't completely exclude it but I think it's unlikely."
Mr Clarke - who served in Tony Blair's government from 1998 to 2006 and lost his seat in Parliament in 2010 - said that, under Mr Miliband, Labour was "not remotely near" providing the necessary narrative of where it felt it succeeded or failed in Government.
He said that critics were right to say Labour spent too much while in power, accusing Gordon Brown of overspending "not very, very dramatically but significantly" between 2006 and 2008.
Mr Miliband now needs to "set out a clear statement of what Labour would actually do - give people a reason to vote Labour, not an assembly of odd policies like the electricity (price) freeze or whatever", he said.
The Labour leader and Ms Cooper were "completely wrong" to apologise for the party's record on immigration, said Mr Clarke, who insisted that the case for giving immediate freedoms for Eastern Europeans to work in the UK was "extremely strong".
"One of my restraints over the last three or four years has been to not attack particularly Yvette and Ed Miliband on what I think are ignorant and ill-informed statements about what happened in this whole process," he said.
Mr Clarke said he could not see any "obvious" replacements for Mr Miliband as leader, and did not think his elder brother David - who left Parliament after losing out to Ed in the 2010 leadership contest - would return to British politics.
He suggested that Mr Blair would have "every chance" of being chosen leader and elected prime minister if he was still a Labour MP, though he conceded that some of his money-making activities since leaving office had "damaged his reputation".
Asked whether former chancellor Alistair Darling would do a better job than Mr Balls as shadow chancellor, Mr Clarke stressed he was "not calling for Ed Balls to go", but added: "I don't think Alistair wants to do it [but] definitely I think it would be better for Labour if Alistair was there rather than Ed Balls."