Tory leadership polls show that Theresa May is ahead, but Boris Johnson is the credible choice

The Conservative leadership election is going to turn on the question of whether someone who advocated staying in the EU can be trusted to negotiate the terms of our exit

Theresa May is 17 points ahead of Boris Johnson according to today’s YouGov poll of Conservative Party members in The Times. That is a pretty decisive margin and the best possible start for the Home Secretary’s leadership campaign, which she is launching at Westminster today.

Opinion polls, you say. Who believes them? Well, I do. They are still the worst way of knowing what people think apart from any other. They were actually reasonably accurate about the referendum: it’s just that we – well, I – put too much weight on their showing which side was ahead when the margin was never emphatic. And YouGov has a remarkable record of predicting major party leadership elections. Its poll of the people who will make the final choice to decide the next prime minister is the best information we have.

But we are right at the start of a 10-week campaign. One of the reasons May is doing so well, I suspect, is her low profile during the referendum campaign. That means she is the invisible candidate in whom Tory members can see what they want to see, against Johnson, who has been all-too-visible, and not always to his advantage, over the past month.

She has her qualities, as the poll confirms. She beats Johnson on strong leader, tough decisions, good in a crisis and “best at negotiating a new relationship with the EU”. This last one is the biggest surprise to me, because I thought her decision to join the Remainers, despite her Eurosceptic record, would mean that Tory members, 63 per cent of whom voted Leave, would regard her as a traitor to their cause.

That will teach me to be swayed by an unrepresentative minority, probably of Ukip members, in the online comments sections.

Yet I do think she has a problem, which will become more apparent now that she has to appear in public and say things. This is not just that party members will remember how dull and uninspiring she can be, but that they will realise the implications of her support for Remain.

I thought Johnson would win because the new prime minister had to be someone who campaigned for Britain to leave the EU. I thought the British people, having voted to leave, are entitled to have as prime minister someone who believes in the policy. So far, that seems less important to Conservative Party members.

Of course the cynics say Johnson doesn’t actually believe in it, having adopted it as a means of getting the top job, and that May, who came down narrowly on the other side of the question, is actually more of a convinced Leaver than he is.

I know that I am, with Daniel Finkelstein, an outlier on this. I think Johnson, when it came to the moment to choose, is a genuine Outer. May really isn’t. In her speech on the subject in April, she said, in effect, that she would be for Leave if it weren’t for the economic argument and Scotland. Which is a bit like saying she would be for Leave if she didn’t believe the opposite.

There are powerful people who are suspicious of Johnson. Sarah Vine wrote to her husband Michael Gove, in the email accidentally copied to a member of the public, that Paul Dacre, editor of the Daily Mail, and Rupert Murdoch, owner of The Sun and The Times, “instinctively dislike Boris but trust your ability enough to support a Boris-Gove ticket”.

I am told that Murdoch met Johnson the week before Johnson changed the course of history by coming out for Brexit, and that Johnson wouldn’t commit himself, if anything implying that he would support David Cameron. Murdoch was indeed unimpressed when Johnson then came out for Leave.

Yet Johnson led the Leave campaign. He put the case to the British people and he won the democratic argument. In the Tory leadership election, he will now pound May over her support for staying in the EU, arguing that a Remainer cannot possibly be expected to negotiate the terms of something that she believes will harm the British national interest. That was, after all, why David Cameron resigned: he recognised that he couldn’t do it and people wouldn’t trust him if he tried.

May is trying to head that attack off by saying she will appoint Johnson or Gove as Secretary of State for Brexit, but it is the prime minister who leads the government.

That is the question on which the Tory leadership campaign now turns: if you accept that the Brexit deal has to be negotiated by someone who believes in it, the next prime minister has to be a Leaver. And Johnson is the only credible one.