In its entire life, the party of Labour has only produced three majority-winning leaders and not one of that rare trio had hands roughened by physical toil. Two of them (Clement Attlee and Tony Blair) were privately educated barristers. The third (Harold Wilson) was a grammar school lad who became an economics don. All three took their degrees at Oxford.

Even so and even now that the party has become very middle class, contenders for the Labour leadership feel compelled to compete to be prolier-than-thou. Sir Keir Starmer, perhaps feeling the burden of the knighthood that he earned for being director of public prosecutions, is keen to stress that his mum was a nurse and his dad a toolmaker and they christened him out of respect for Labour’s first leader, Keir Hardie, a miner.

A more persuasive way of establishing Mr Starmer’s credentials as a man of the left was the campaign video that projected his legal career in a way tailored to appeal to Labour members. It highlighted the cases he fought on behalf of dockers, print and pit workers, poll tax protesters, environmental campaigners and the family of Stephen Lawrence. Even rival camps acknowledge that this was a smart way of pre-rebutting any attack on him as an establishment QC and recasting “Sir Keir” as the heroic legal freedom fighter, Superlawyer. When he and other contenders performed at a hustings for Labour MPs last week, it was a compliment to the effectiveness of this pitch that it was aped by one of his competitors, Emily Thornberry.

By general consent and rather against the run of expectations in the immediate aftermath of the election defeat, Mr Starmer’s campaign to be Labour’s next leader has got off to the strongest start. It is least surprising that he has mustered the most nominations from MPs, many of whom see him as the best available answer to their yearning for someone who can at least turn them into an effective opposition for the next five years. It was a significant boost to attract the backing of Unison, the largest of the trade unions and one that represents many low-paid workers. He is presenting himself as a unifier and his campaign team is ideologically diverse enough to embrace both people who have worked for Jeremy Corbyn and those who have organised for Liz Kendall, the most Blairite of the candidates in the 2015 leadership contest. The first, and so far only, poll of the party’s members has suggested that he is ahead of the following pack.

Facebook Twitter Pinterest ‘In Rebecca Long Bailey, the hard left has a candidate who appears unsure whether she truly wants to be the torchbearer for continuity Corbynism.’ Photograph: Bloomberg/Bloomberg via Getty Images

This tells us that the devastating scale of Labour’s losses in the December election has been a salutary shock to at least some of the party. The calamity inflicted by Corbynism’s deadly combination of ideological zealotry, toxic factionalism and rank amateurism commends professionalism, pleasantness and credibility to any members who are fed up with losing and would prefer not to be doomed to another decade in opposition. I have heard of a lot of examples of Labour activists who voted for Mr Corbyn in the last two leadership contests and who now intend to back Mr Starmer. He has also been blessed by his rivals. In Rebecca Long Bailey, the hard left has a candidate who appears unsure whether she truly wants to be the torchbearer for continuity Corbynism. She has given Mr Corbyn “10 out of 10” for leadership, prompting mirthful wonderment about how she would have ranked him had he won the election rather than crush Labour’s parliamentary representation down to the lowest level since 1935. The more revealing dimension of her candidacy is the bitter divisions within the hard left about whether she ought to be their representative and her hesitancy about taking on the role of heir to Corbyn for which she has long been groomed and promoted. “Rebecca is quite shy,” says a not unsympathetic Labour MP. “If you bump into her in a corridor, she never says hello unless you say hello first. I get the impression that she’s struggled to make herself do it.”

The presence of Jess Phillips as a competitor is probably a net positive for Mr Starmer and it could suit him if the Birmingham MP gathers enough nominations to get into the contest proper. He does not have to be absolutely brutal with the party about its desperate plight when the unflinching Ms Phillips is there to be the blunt truth-teller of the contest. Anti-Corbynite people are joining or rejoining the party in order to support her. Their second or third preferences are likely in large part to go to him.

None of which means that it is all wrapped up. Far from it. It is a long and hazard-strewn road to the finishing post of this contest, the result of which will not be revealed until early April. If it gets its act together, the hard left has considerable organisational heft and a significant capacity to turn things extremely ugly. Len McCluskey’s Unite will throw its resources and bureaucracy behind Ms Long Bailey. The campaigns of Lisa Nandy and Ms Phillips might take flight. There is still quite a lot of resistance to the idea that the next Labour leader should be another bloke who lives in north London.

Facebook Twitter Pinterest Mr Starmer does not have to be absolutely brutal with the party about its desperate plight when the unflinching Jess Phillips is there to be the blunt truth-teller of the contest.’ Photograph: Wiktor Szymanowicz/Barcroft Media

Mr Starmer will find there is a price to pay for being the front runner, which is that you get exposed to searching questions about who you are and what you really stand for. Gathering opinions among his supporters, I find that they tend to commend him mainly on the grounds that he has the ability and the character to perform the role. “Keir is the only grown-up,” is a typical sort of answer. Another goes: “Keir is the only person the public can see standing on the steps of Number 10.” One supportive Labour MP says: “I don’t really know exactly where he is on the ideological spectrum, but I don’t particularly care. I trust him to do what needs to be done.”

He demonstrated his ability to do a big job as DPP when he successfully led a complex and often very challenged organisation. As the party’s Brexit spokesman, he navigated Labour’s divisions as well as anyone could. The well-organised start to his campaign – “he’s got a plan, he’s got a grid,” says one admirer – is taken as another sign that he would be an effective team leader. “He’s absolutely contemptuous of the way Corbyn and his crew ran the Labour party. He sees them as incompetent as well as nasty,” says a friend of many decades standing.

Then there are the doubts. No one questions his intellectual ability, but many do wonder about his capacity to inspire. “Keir’s legalistic scalpel is his greatest strength and his greatest weakness,” remarks someone who sat with him in the shadow cabinet. They know he can do forensic scrutiny of the government in parliament; they don’t know if he can galvanise opposition to Boris Johnson’s Tories out in the country. “Let’s be honest,” says one Labour MP. “He can be bloody boring.”

His ideological definition is fuzzy and he has offered only a vague diagnosis of why the party suffered such a calamitous election defeat. He has expressed some sympathy with the critique that Labour’s gift catalogue manifesto was simply incredible in the eyes of many voters. Yet he has tried to offer reassurance to the party’s left by saying that he wouldn’t “oversteer” away from Corbynism to the right. He has studiously avoided identifying which elements of Labour’s rejected election offer he would junk. It is not clear what this adds up to, even among his supporters. “He is decent. He is a moral leftwinger,” offers one. “He has no fixed ideas on policy.”

This lack of any very exact definition has served him well so far. He has the goodwill of figures closely associated with the New Labour years, a lot of backing from the soft left of the party and at the same time is attracting support from some of the more pragmatic elements of Corbynism. There are inherent contradictions in such a broad coalition and they can’t be avoided forever. Some of his supporters commend his reluctance to pick any ideological fights when there is a leadership contest to get through first and it won’t be won by telling the members that they’ve been completely wrong for the past four years. One Starmer-backing senior Labour figure quoted to me with approval an aphorism of Harold Wilson: “The art of being a successful party leader is to turn angles into curves.”

Mr Starmer is on an upward curve at the moment, but he is unlikely to get through this protracted contest without confronting at least some of Labour’s many jagged angles.

• Andrew Rawnsley is Chief Political Commentator of the Observer