Former Prime Minister Tony Blair has cast doubt on whether Labour can win the general election.
The former Labour leader predicted a Tory win in 2015 unless his party revived the spirit of "New Labour" and moved into the centre ground.
Mr Miliband has committed his party to what many commentators see as left-wing policies, including the freezing of energy prices and the reinstatement of the 50p top rate of income tax.
In an interview with the Economist, Mr Blair said the election could be one "in which a traditional left-wing party competes with a traditional right-wing party, with the traditional result".
Asked if he meant a Tory win, Mr Blair replied: "Yes, that is what happens."
In what could be seen as an attack on Mr Miliband's leadership, Mr Blair said Labour performs best when it is occupying the centre ground.
He said: "I am still very much New Labour and Ed would not describe himself in that way, so there is obviously a difference there.
"I am convinced the Labour Party succeeds best when it is in the centre ground".