Is Boris Johnson about to fall into an election panic?

Laura Kuenssberg, the BBC political editor, reported yesterday that there was nervousness in the Conservative election HQ entering the final week of the campaign. Is this just an attempt by the Tory campaign chiefs to warn their activists against complacency, or are there good reasons for Boris Johnson to be worried?

The main reason is that an average 10-point lead in the opinion polls is not enough to be sure of victory. Although that translates into a majority of 24 seats in parliament, according to Electoral Calculus, this is sensitive to small changes in the share of the vote. It would take only 2 per cent of voters to switch sides to wipe out that small majority altogether – or an error in the opinion polls of an equivalent size.

Indeed, The Independent’s own pollster, BMG, is at one end of the range of estimates of public opinion, showing a six-point lead for the Conservatives, which could produce exactly the same election result as last time.

If Johnson won the same number of seats as Theresa May, 318, it would leave him four seats short of a majority and needing the support of the Democratic Unionist Party again – there are no other parties likely to send MPs to Westminster that could plausibly keep Johnson in No 10.

That is a scenario that might be designed to give Tory strategists nightmares. The DUP is opposed to Johnson’s Brexit deal, and is aggrieved by what it sees as the prime minister’s betrayal of not just the party but the whole of Northern Ireland. The DUP might be even harder to deal with if it has lost Nigel Dodds, its Westminster leader, whose Belfast North seat is odds-on to fall to Sinn Fein.

It is still hard to imagine the DUP putting Jeremy Corbyn, whom it regards as an IRA sympathiser, in No 10 – but even so, Johnson cannot expect an easy time if he needs DUP votes.

The Conservative campaign has lived from the start with the fear that most of the opinion polls are going to get the election wrong, as they did last time. All the pollsters who did get it wrong have changed their methods since then, but no one can be sure that they have corrected for their errors until the day after the election.

But what makes Tory strategists really nervous is the possibility that opinion could shift against them late in the campaign. Tonight’s head-to-head TV debate between Johnson and Corbyn is plainly a higher-risk event for the frontrunner than for the underdog.

And Tories may also be nervous about Deltapoll’s findings for Prospect magazine that suggest voters are bored with Brexit in the final phase of the election, and might have their heads turned by Labour’s big spending promises. Martin Boon of Deltapoll has experimented with an Emotional Resonance Score based on how quickly people answer online poll questions, and says “Corbyn’s vow to plough a vast £150bn into schools, hospitals and housing” gets as good a rating as “the Tories’ pledge of an extra 20,000 police officers”.

If Labour’s spending pledges gain unexpected traction in the final week, Boris Johnson may find, on 13 December, that the Tories’ nightmare has come true.