Simply the best: let’s talk about those ‘Best Prime Minister’ polls

Over the past three years, those of us who support Jeremy Corbyn’s leadership of the Labour Party have heard more or less every criticism under the sun. Public opinion polls, and Labour’s performance in them, have been one of the many criticisms heaped upon Corbyn by the commentariat and the Labour right. Every Conservative lead has been instantly trumpeted as the final ‘proof’ of Corbyn’s unelectability, even after Corbyn turned a 25pt Conservative poll lead into a 2pt lead in the space of two months back in 2017. But even when the standard voting intention polls look fine for Labour (or even good), Corbyn’s critics always have one reliable poll question that they cite over and over again – “Who would make the best Prime Minister?”.

So let’s talk a bit about this question, and how it might not mean as much as Corbyn’s critics think. 

Background 

Since Theresa May become PM in July 2016, pollsters have begun asking this question more and more. It is now a standard feature of polls published by YouGov and Opinium, as well as occasionally being asked by other pollsters. It’s a simple enough question: pollsters ask voters to pick the person they think would make the “best” Prime Minister, asking them to pick between May and Corbyn. Most pollsters include ‘don’t know’ as an option; some add ‘neither’ or ‘none’ as another option.

So what sort of results do these polls show?

Well, in July 2016, when May became Prime Minister, here’s what the polls said on average: 

Theresa May – 52%
Jeremy Corbyn – 18%
Don’t Know/Neither – 31% 

Meanwhile, here’s the average result for September 2018: 

Theresa May – 35%
Jeremy Corbyn – 26%
Don’t Know/Neither – 39% 

The table below shows the average result for each party leader on this question since May became Prime Minister in July 2016.

So, why does this matter? 

Since Corbyn consistently polls behind May on this question, these polls are constantly cited by Corbyn’s critics as proof that Corbyn is an electoral liability, and that it is him personally that the electorate do not like. Thus, they say, if we got rid of Corbyn, Labour would skyrocket in support and be 20pts ahead in the polls.

Yet even setting aside the fact that Corbyn has shown himself to be fully capable of turning around public opinion (between April and June 2017, his standing in the ‘best PM’ polls improved by 20pts), this argument is weak. Here's why.

Are pollsters really asking the right question? 

All of the various poll companies have a slightly different way of asking the ‘best PM’ question:

• YouGov, Survation and Lord Ashcroft ask: “Which of the following do you think would make the best Prime Minister?”
• Opinium ask: “Which, if any, of the following people do you think would be the best Prime Minister?”
• Ipsos MORI ask: “Who do you think would make the most capable Prime Minister?”
• Kantar Public ask: “Who do you think would make the best leader for Britain?”
• And finally, BMG Research ask: “Who would you prefer to see as the next Prime Minister?”

There is a notable exception in that list: uniquely, BMG Research asks voters to tell them who they want to be Prime Minister, not just who they think would be the “best” at the job. All the other pollsters ask voters to express a judgement on which party leader would perform best at the role of Prime Minister: looking the part, acting like a PM, going on all the international trips abroad, attending summits, handling diplomacy – things like that. But that’s not a value judgement - it’s not even a question about competence. 

It’s basically asking people: who do you think would be better at being Prime Minister? The person who is Prime Minister, or somebody who isn’t? The answer is pretty obvious to most people.

This difference in wording is reflected in the data. BMG consistently shows poorer results for Theresa May than either YouGov or Opinium, the only other pollsters to publish a monthly figure for 'best PM'. Sometimes BMG shows May doing 10pts worse than YouGov. That’s not just a difference in sampling or turnout weightings – that’s the consequence of asking people a different kind of question. 

When you ask voters who would make the “best” Prime Minister, more people say May. When you ask voters who they want to be Prime Minister, May’s commanding lead vanishes like a puff of smoke. That’s worth thinking about.
 

Does any of this even matter? 

The reason why Corbyn’s critics keep pointing to these polls is because they think the public will refuse to vote Labour because of the leadership, and that the question of who makes the “best” Prime Minister is very important in determining voting intention. But survey data suggests that this isn’t even true.

Following the 2017 general election, YouGov asked voters to tell them the main reason why they backed Labour or the Conservatives in the general election. 17% of Labour voters cited their support of Jeremy Corbyn or their opposition to Theresa May as a reason. Meanwhile, 19% of Conservatives cited their support of Theresa May or their opposition to Corbyn as a reason.

In other words, for over 80% of the two major parties’ voters, the merits or weaknesses of the party leaders were less important than issues like education, Brexit or policy generally. And this remains the case today. In a recent YouGov poll, just 7% of voters said that “Which party's leader would make the best Prime Minister” was the most important issue in deciding their vote. To over 90% of voters (and over 95% of Labour voters) there are much more important things on their mind when they go to the polling station.

So in the end, whilst it’s interesting to note the differences between BMG’s polling and YouGov’s polling, to most voters the question of who makes the “best” Prime Minister is pretty unimportant. If Corbyn’s critics want to become relevant in the Labour Party again, they really need to stop obsessing over opinion polls and focus on developing an actual policy programme – such as Corbyn’s promise to nationalise the water industry, a policy which one poll suggests is backed by 59% of the British public. That’s one poll that you won't hear about from Corbyn's critics.

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