Peter Mandelson, one of the key architects of New Labour, has said that the politics of the Blair-era government was over and that it is time for a new generation with new ideas.
Lord Mandelson, who together with Tony Blair and Gordon Brown founded the New Labour politics which defined the latter part of the 1990s and the early 2000s, said that the party had moved on.
Asked by Jeremy Vine on The Andrew Marr show, on BBC One, whether he would stage a return to frontline politics if invited to do so by Ed Miliband, he said: "Well I don't think he's likely to do that because what he's trying to demonstrate is that sort of Blair, Brown, sort of Mandelson era, you know, ended when we lost power in May 2010 and that he's moving on with a new generation with new ideas."
He added: "I'm available indeed, but to support him from the sidelines."
The former Cabinet minister insisted he approved of Mr Miliband's "One Nation" Labour, but said it was important to show that the policy changes matched the party's repositioning.
"You need to put the contents in the tin," he said. "The label is good but you have got to make sure you have the policies to back it up."
When asked if he would sack Ed Balls, Lord Mandelson said he would not.
"What he's got to do is to show that he is not simply a business as usual politician and the Labour Party are simply going to carry on exactly the same policies of the present coalition Government or even, to a certain extent, some of the policies of the previous New Labour government," he said.
"Now that's harder to do - to show, at a time when many in the public are very sceptical about any politician's ability to deliver anything at all, to demonstrate how he is going to make a difference. I think he has started well on that course. By his own admission, he has still some further way to travel."
Lord Mandelson, who was previously in favour of a referendum on European, said he was now opposed to such a vote.
Pulling out of the EU would be "a great setback" for the British economy, he said.
The Labour left ideology of Tony Blair shaped Britain for a decade and was still felt in UK politics long after he stepped down as prime minister in 2007.
Blair's loyalists are still around although some have fared better than others. See the slideshow below