All sides of the Remain campaign are turning their fire on Boris Johnson at the moment. But these attacks are, I argue in The Sun today, a mistake by the Remainers.

First, it makes Boris, the most popular politician in the country, the face of the Out campaign when the IN campaign’s strategic aim is to make voters think that Nigel Farage embodies the Out case. Second, it means that the whole referendum is seen through the prism of the Tory leadership. This is not only bad for Tory party unity post-referendum, but also makes it harder for IN campaign to get the support of Labour party voters as it drowns out Labour’s own message.

Senior figures in the Remain campaign think that the attacks on Boris work because, they claim, he is seen as being out for himself and a hypocrite. But the Remainers have forgotten what the Tory modernisers used to know, that what you say about your opponent—and how you say it—says more to the voter about you than them. Going after Boris in such a personal way just made Remain look rattled.

The Leave side, though, know that the IN campaign have more ammunition to fire off to try and get the debate back onto the economy. The IMF and the Bank of England will both make interventions before June 23

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and George Osborne will deliver the Mansion House speech on Thursday.

But, at the moment, the Remain side are having a jittery moment. The question is whether this is just the public flirting with Out, before settling down with the status quo. Or, whether this referendum is going to be much, much closer than Westminster expected.