Jeremy Corbyn has vowed to prevent a disastrous Labour split by promising to invite “great talents” from all wings of the party – including Blairites – into his shadow cabinet if he becomes leader.

His offer to involve people with sharply different views, coupled with a pledge of radical reform to make policymaking more democratic, comes as former leader Neil Kinnock throws his support behind Andy Burnham and warns that “Trotskyite” forces with “malign” intentions are trying to drag Labour to the far left under Corbyn.

The party’s deep divisions were further underlined on Saturday as the final list of nominations from constituency Labour parties (CLPs), unions, MEPs and affiliated organisations showed Corbyn ahead with 162 to Yvette Cooper’s 121, Burnham’s 118 and Liz Kendall’s 21.

Among CLPs alone, Corbyn won the backing of 152, Burnham 111, Cooper 106 and Kendall 18.

In an interview with the Observer, Corbyn spells out a strikingly leftwing agenda, calling for higher wages for public sector workers, higher public spending, more collective bargaining in the workplace and renationalisation of key services, including the railways and those parts of Royal Mail that have been “hived off” to the private sector.

But he promises that if he won he would be “big enough” to bind all Labour voices and talents into decision and policy-making processes and says that if the party stuck together it could win the next general election under his leadership.

Corbyn reveals that he intends to order a radical reorganisation under which Labour MPs would vote for policy teams that would work with individual shadow ministers, ending what he calls the “top down” approaches developed under Tony Blair and New Labour. Asked whether he would want Blairites, including fellow leadership contender Kendall – who has said she would not serve in his shadow cabinet – in his team, he says: “Yes. I want people to come in. There are people with great talents, and OK, people do have political differences and there is nothing wrong in having those political differences. Of course there are differences of opinion and I have got to be big enough to accommodate those, and I understand that. Some of my colleagues have said they would not be very keen on working with me, but I am sure these things were said in the heat of the moment.”

Jeremy Corbyn: ‘This is the most open democratic election Labour has ever had’ Read more

However, Kinnock, writing in the Observer, urges “true Labour people” to fight back against what he calls Trotskyite forces backing Corbyn. Kinnock – the first former party leader to commit support to a candidate – says he understands the “rage” that is compelling many genuine members to support Corbyn, but insists the party must choose its leader with “sincerity and realism”. He warns that a Corbyn victory would turn the party into a powerless “discussion group”.

The Labour grandee, who battled against the Militant left during his leadership in the 1980s, writes: “In the leadership election, we are not choosing the chair of a discussion group who can preside over two years or more of fascinating debate while the Tories play hell with cuts in local services and public investment, extend injustice and flatlining incomes, sustain or worsen private debt, deepen the balance of payments, productivity, housing and poverty deficits. We have to elect a leader capable of taking us to victory in the 2020 election and of being Labour prime minister.

“The Trotskyite left and the Telegraph right who might participate in this election clearly have their own malign purposes. I hope that everyone else voting in the leadership election – the great majority who are true Labour people – will make their decision with the greatest possible sincerity and realism. For us, and for those people of all ages and every condition who we seek to help and advance, it won’t be enough to protest – our ideas and ideals must appeal and prevail.

“That will require huge, consistent, united efforts by the party. It will need policies that are strongly rooted in Labour values of care, opportunity, security, fairness and freedom.”

In a sign that he is now preparing for the possibility of victory, Corbyn – regarded as the rank outsider a few weeks ago – says he had been thinking hard about how to involve MPs across all wings of the party in decision-making. He insists, however, that whatever the result it would be up to everyone in the party to pull together and recognise that the new leader would have been chosen in the most open, democratic vote in Labour’s history. “I hope that they would recognise that party members have put an enormous amount of time and effort into this whole election debate, and I think that should be recognised.”

Kendall, who today announces plans to spend £1bn, to be raised from reversing Tory cuts to inheritance tax, on services to help pre-school children and their parents, concedes that Corbyn is clearly ahead in the race. She says Labour will have no chance of winning the next election under Corbyn, and could fare worse than in its disastrous defeat in May.

But she insists there is still time to turn the tables and convince Labour members to vote for a candidate who would be both true to Labour’s values and have a chance of ousting the Tories in 2020. Referring to the surge in interest and support for Corbyn she says: “He is doing well. I think party members are desperate for an alternative to where we have been for the last five years and they want hope for the future but Jeremy Corbyn does not have a monopoly on hope or a monopoly on setting out an alternative.

“They are angry about what has happened. For the remaining six weeks of the campaign I am going to be setting out our credible alternative of hope for the future.”

Polling by market research company Research Now suggests that more people across the whole population would vote for Burnham as the next Labour leader, regardless of their political affiliation. Of those interested in the leadership election 30% say they would vote for Burnham against 24% who would choose Corbyn.