The meek vs the geek: Brothers Miliband battle it out

Their famous father Ralph was a Marxist, but David and Ed tread a centrist path

Ralph Miliband was a grateful refugee into this country, but he was not blind to its failings. The doyen of Britain's Marxist historians reached the UK in 1940, after walking 60 miles with his father to catch the last boat from Belgium. Soon after he arrived, he found Karl Marx's grave in Highgate Cemetery and, railing against the inequalities he found in the EastEnd of London, swore "my own private oath that I would be faithful to the workers' cause".

Nearly 70 years on, and almost 16 years to the day after his death, the radical's most celebrated legacy to the workers' cause – and British politics in general – may be to provide the two main candidates for the leadership of a middle-of-the-road social democratic party.

David and Ed Miliband will carry their father's name into the contest for the Labour leadership over the next few weeks, but the attitudes of a man who once bemoaned "the sickness of Labourism", will not inform the debate.

The brothers confidently expect their mother, Marion Kozak, to remain neutral. "This is a cause she is going to have to sit out," David said after his launch last week, although Ed yesterday joked that, "on the basis of her position on the political spectrum," she was more likely to support left-winger Jon Cruddas.

The scant details in the "manifestos" laid out by each of his sons focus on criticising Labour's failure to connect with voters in the general election campaign, rather than the party's record in government."We have achieved a great deal in government but this is a new era with new dangers, opportunities and possibilities," David said, before embarking on a nationwide tour to find out what went wrong.

Ed was a little more critical during his campaign-launching speech in London yesterday, when he said "New Labour's combination of free markets plus redistribution reached its limits a few years back," but he remained resolutely supportive of the centrist message.

The Miliband parents could not be accused of not trying to convince their sons of the socialist case for a class-based approach to politics. Their north London home was a gathering-place for some of Britain's most famous left-wing intellectuals while their sons were growing up, and both were often active contributors to the parlour debates that followed. David once spoke fondly of answering the front door to find Joe Slovo, a leader of the military wing of the African National Congress, standing on the doorstep.

At around the same time, Miliband Snr managed to get his eldest a placement with the then GLC leader Ken Livingstone, but the experience did not spark a reordering of his political views. "David did some work for me," Red Ken recalled, "but he had a way of looking at me as if I was a dangerous radical."

Ed Miliband did at least start a little closer to his father's position, working for left-wing MP Tony Benn before moving on to Harriet Harman and then Gordon Brown. Although he took his sons to campaign for Labour, he never quite adjusted to its drift towards the centre; his children, in contrast, were in at the ground floor of the New Labour revolution.

Mr Benn later wrote that Ralph Miliband was sometimes bewildered by the way his sons questioned his attitudes, and worried that he was "very out of date".

"I think he would have disliked lots of what the [New Labour] government has done," Ed has acknowledged, "but I think he would have understood why we worked with it. He thought very much that we should do what was right for us. He didn't think we needed to follow his path."

Thus, the youngest son of the intellectual who wrote books including Class Power and State Power and Divided Societies: Class Struggle in Contemporary Capitalism, stood before a New Labour audience yesterday and insisted the party of Blair and Brown was still "the best vehicle for people's hopes and people's aspirations".

This was an audience of people from the Fabian Society and the Labour Party and Ed was preaching to the converted. The former energy secretary was given a standing ovation even before he began speaking to a packed auditorium at the School of Oriental and African Studies (SOAS).

Ed admitted that Labour had lost the election because "we lost touch with the lives of the people we represent" and "we lost touch with the values that made us a progressive force in politics". He also said he was "absolutely" ready to serve under David if his brother was to win. Their father might not have appreciated such willingness to compromise.

However, inside the arena, online campaigner Luke Bozier was enthused. He said: "He has the common touch, which is crucial. While David is obviously very clever, he can seem a bit aloof. Ed is really good at connecting with young people."

As if to illustrate his point, a group of young people gathered on the steps outside SOAS, waving placards bearing slogans such as "Ed 4 Leader" written in red paint. Joe Powell, who was holding a banner reading "Ed Speaks Human", said: "I think he is serious about leading the green economy and comfortable with the unions and the private sector.

"The unions are important because they represent a lot of the people that the Labour Party was set up to represent. He can unite us as a party."

It became clear last night that the younger Miliband will almost certainly face an uncomfortable contest against another of his closest colleagues, as former schools secretary Ed Balls prepared to announce his bid for the leadership.

Mr Balls, another key Gordon Brown ally, will meet local activists in his Yorkshire constituency today before deciding whether to mount a formal challenge. But, amid growing expectation that he will enter the fray, aides confirmed he had the support of several senior figures, including the Blairite former defence minister Eric Joyce – and three more are already lined up to run his campaign.

Mr Balls said: "I'm going to talk to my campaign team. I want to listen to their views first and then make an announcement. This leadership election is a great opportunity for us, but there's also a danger.

"The opportunity is to engage our party members, to have a debate about what's happened, to make sure that we get things right for the future. But we must make sure that we don't decide and then tell voters. I think we've got to start by listening to voters first and hearing what they're saying to us."

A fourth former special adviser who worked his way up into a Labour Cabinet, Andy Burnham, the former health secretary, is also believed to be seriously considering a leadership bid.

Mr Cruddas, who is expected to stand as the only left-wing candidate, prepared the ground for his campaign yesterday, with an attack on New Labour tactics, including the reliance on focus groups to guide policy.

The Dagenham and Rainham MP, who ran against Ms Harman for deputy leader in 2006, told Prospect magazine: "Early Blair was brilliant when he talked about rights and responsibilities, but the focus groups destroyed that – he lost that ethic. Because his coalition was splintering he sought to dig even deeper into that middle ground rather than build something broader, wider, deeper."

David Miliband

"The Brainy One"

Age 44

Height 5ft 11in

Nickname Brains – as in the Thunderbirds' scientific genius

Education Haverstock comprehensive, north London, Oxford University, Massachusetts Institute of Technology

Family Married to violinist Louise Shackleton; they have two children

Reputation Nerdy, but able

Ed Miliband

"The Nerdy One"

Age 40

Height 5ft 11in

Nickname Emissary from the Planet Fuck – given him during 2001 election, when he was the Brown camp's go-between with Blairites

Education Haverstock comprehensive, Oxford University.

Family Lives with partner, barrister Justine Thornton, and their son.

Reputation Just as nerdy as his brother, just as able, but a bit more human

Other possibles... still to decide

Ed Balls

"The Tough One"

Age 43

Nickname Blinky

Education Private all-boys Nottingham High School, Keble College, Oxford, Harvard University

Family Married to fellow MP and former Cabinet minister Yvette Cooper, they have three children

Reputation Once seen as a bit thuggish, becoming softer

Andy Burnham

"The Pretty One"

Age 40

Nickname Flog 'em and Burnham, for his hard line as a Home Office minister

Education St Aelred's RC high, Newton-le-Willows and Fitzwilliam College, Cambridge

Family Lives with his wife, Marie-France van Heel, their three children

Reputation Thoroughly decent, becoming more robust. Great eyelashes.

Jon Cruddas

"The Lefty One"

Age 48

Nickname None known

Education Oaklands RC comprehensive, Waterlooville, University of Warwick, University of Wisconsin–Madison

Family Married fellow Labour activist Anna Mary Healy; they have one son

Reputation Genuine conscience of the left, critic of the Blairite rush for the middle classes.