Over the next few months, the Labour leadership candidates will seek to woo you with a non-stop assault of speeches, interviews, platitudes and policy documents. Not to mention endless retweets of endorsements on Twitter. There will be no escape.

Given the mountain that Labour has to climb to win in 2020, what we need aren’t more endless cliches about ‘aspirational’ voters or ‘being pro-business’, we need a serious debate about the main challenges the party faces. Last week I spoke to Cambridge Uni Labour about three of them.

Grappling with English nationalism

It was partly the forces of nationalism that killed us. In Scotland it was the SNP positioning themselves as the new standard-bearers of the Scots. In England, by raising the dangerous spectre of Miliband being held to ransom by the SNP, it was a sense of English nationalism that killed us. People felt Labour just could not be trusted to protect England’s interests against the SNP.

But this isn’t just economic. A large part of Labour’s loss of connection with working class voters is cultural, not economic; they feel the leadership doesn’t connect with them. As the former MP John Denham pointed out:

When people cast their vote, many now think as much about what it means for their nation and their community as they do about party policies for economic and social justice. The role that class once played in defining ‘people like me’ is being replaced by a more communitarian sense of belonging. Labour activists usually wish this wasn’t true but it was. Our failure to recognise, let alone address, the central importance of the politics of belonging was the single unifying thread of our disappointment.

And Mary Riddell is right when she says:

Mr Miliband’s problem was not that he veered too far Left or Right, since Mr Farage and Ms Sturgeon outflanked him on either side, but that he failed to tell a national story that would touch the soul of voters.

The time for a serious debate within the Labour party on English nationalism – not as a reaction to others in Scotland, Wales and NI, but to include them as part of the conversation – has come. Only a Labour party confident about English identity can seriously learn to understand and debate Scottish nationalism.

Will any candidate grapple with this debate with honesty and eagerness? Can they show they can culturally connect with voters, not just reel out a list of policies?

Tackling inequality versus ‘aspiration’

Ed Miliband’s analysis of the economy was absolutely right – that it has stopped working for ordinary people – but failed to deliver a vision that was attractive to voters. He touted pre-distribution but ended up resorting to traditional tax-and-spend policies to reach voters (Mansion Tax, 50px etc).

So the dilemma for the next Labour leader is the same: how to fundamentally change the economy so it works for people, without scaring off Middle England.

Can they convince people that the economy needs deep, fundamental change?

What ideas do they have to raise the wages of the poorest?

How can they convince Middle England that inequality needs to be challenged?

There is little doubt that Labour has to appeal to wider pool of voters than we did over the last five years. But can we do that while still convincing them of our core mission? How?

Cosmopolitan voters versus Middle England voters

Labour voters are now primarily based in big cities across England. We cannot afford to ignore them, as the Economist’s Jeremy Cliffe pointed out in a paper last week called Britain’s Cosmopolitan Future. They like urbanisation, are comfortable with immigration and diversity, and liberal in their outlook. If ignored or dismissed, they will likely defect to the Greens or Lib Dems. They are now the Labour party base.

But they can’t help us win elections alone. London, Manchester, Birmingham, Leeds, Liverpool etc are not enough to win a majority in the Commons. So, Labour has to appeal to voters who went over to UKIP and/or see themselves as small-c Middle England. Just regurgitating harsh rhetoric on immigration or welfare won’t sound credible, and likely to alienate our base. So how can we culturally connect to these increasingly polarised groups?

Over the next few months the Labour leadership candidates will seek your votes. Based on the disastrous election we just went through, here is my advice: don’t necessarily choose the candidate you most like (they’re not that far apart).

Look for the candidate who recognises their own weakness and seeks to deal with them quickly. Choose the candidate who adapts, and is decisive and bold.Ask them about the big contradictions and challenges that Labour faces, and look for the one with the capacity and imagination to surprise you. That is the candidate most likely to win.