Will Keir Starmer enjoy the shortest ever honeymoon as prime minister?

It is amazing how many things that would be a problem if you were not 20 points ahead in the opinion polls are not a problem if you are 20 points ahead.

Professor Sir John Curtice, the psephologist, said it well this week: “You’re looking at a party that has been gifted this election. I think the problem the Labour Party should start worrying about is how to maintain popularity after they win.”

Keir Starmer’s ruthlessness in doing what it takes to win the election, and to take nothing for granted, is admirable in its way. But the promise to borrow £28bn a year – although terms and conditions applied – was obviously a potential liability and should have been abandoned months ago. And at some point, a candidate prime minister needs to devote a certain amount of compartmentalised time and staff resources to the question of what happens after polling day.

That is what Starmer and Rachel Reeves, the shadow chancellor, think they are doing. The reason the £28bn was junked was that the Labour leader set a deadline for submissions for the manifesto, and it became obvious that this was a number that they couldn’t put in it. But the arguments against it were more to do with war-gaming the election campaign than with preparing for government.

Labour knew how important it was, in fighting an election, that “the sums always add up” – Rachel Reeves’s words on Friday. So they have belatedly and inelegantly fixed that problem, while leaving the question of what they will actually do in government patently unfixed.

As a former Labour special adviser said to me, it is only now that the £28bn has been stood down that “people are talking about what it would have paid for – it got in the way of talking about what actually needs to be done with the money; it was classic big statism for the sake of it”.

More worryingly, the retreat suggests that “Starmer needs to be biffed on the nose by a problem – see also gender self-ID – before he deals with it, which bodes ill for what he’ll be like in office”.

Sure enough, here is the next problem that he doesn’t seem to have seen coming: the £28bn has gone, but the “mission” for which it was supposed to pay remains. Labour promises that the entire UK electricity supply will be carbon-free by 2030. This is a target that people in the energy industry think would be impossible even with unlimited funding, and yet Starmer and Reeves say they will achieve it with less funding than they were promising before.

Professor Dieter Helm, who was Reeves’s economics tutor at Oxford, is scathing in the Financial Times: “Having set an unachievable target, and then come up with an incoherent plan to achieve it, the plan has effectively been abandoned but the target remains. This is not a credible energy policy.”

It is not clear which is more worrying: that Starmer and Reeves don’t know that the target is green pie in the sky, or that they don’t care. Maybe they hope to swivel once in office to say that they never thought they would hit it; what they meant was that they would try really hard to get there faster than a Conservative government would – the Conservative target of 2035 is after all already testing enough.

Reeves admitted that 2030 is a “stretching target”; James Murray, a junior shadow Treasury minister, said it was Labour’s “ambition”; Starmer himself recently called it a “confident ambition”, which it may be until such time as it becomes an unconfident one.

Which will be very soon after Starmer, if elected, takes office. Maybe most voters won’t care, but many core Labour voters, who are deeply concerned about the climate emergency, will be upset. It may be that Starmer can afford to lose one part of his electoral coalition – except that the situation he will inherit will be so difficult that it is hard to see which part of his coalition he can retain for more than a few months.

How quickly, for example, will voters be disappointed that the new government has failed to raise living standards, cut NHS waiting lists, or build extra houses? The last time a new Labour government came to power, the economy was in good shape, thanks to the responsible stewardship of Norman Lamont and Ken Clarke. Partly because of that, people were prepared to give Tony Blair time to learn on the job.

This time, taxes will need to rise or public spending will need to be cut, thanks to the “bare cupboards” policy of Jeremy Hunt. Labour seems unprepared for the difficult decisions it will face.

Even if Blair sends a copy of his new book to Starmer when it is published in September, the lessons New Labour learned in government, while useful, will not help to magic away the reality of the ruined public finances. Blair says On Leadership: A Practical Guide is the manual on political leadership that he would have wanted in 1997, but it cannot change the different nature of Starmer’s likely inheritance.

I fear that Starmer will have the shortest-ever honeymoon as prime minister, and that the new government will become unpopular very quickly.