We’ve had two “new” polls on EU membership this week (the inverted commas are there becuase while the ICM poll out today has fresh fieldwork, the ComRes poll earlier in the week was actually done at the end of September). ICM’s latest figures have REMAIN on 44%, LEAVE on 39% (tabs). ComRes meanwhile had REMAIN on 55%, LEAVE on 36% – a far more solid lead for those wishing to stay in the EU (tabs)
There is obviously sizeable gulf in the figures different polling companies are reporting on the EU referendum. ComRes have done several polls on the EU referendum since the election and have consistently shown REMAIN with a strong lead, in contrast two YouGov polls last month both showed LEAVE with a small lead (though they had been showing a modest lead for stay earlier in the year). ICM have been conducting a weekly tracker on EU voting intention, and their figures tend to show a modest lead for those who want to stay.
Polling methodology is in a period of flux as pollsters reassess their approaches in the light of what went wrong at the general election, but I don’t think that explains the difference here. ComRes have indeed adopted a new turnout model based on socio-economic factors… but the nineteen point lead is without that extra turnout weighting, it would be even bigger with it. It could be a online vs telephone difference – YouGov and the regular ICM tracker are both conducted online, the ComRes polls by telephone – but that’s hardly enough evidence to be confident, there will be many other differences in methodology.
While we can’t really tell why there is a difference, we can say where the difference is: Conservative voters. All three pollsters have Labour voters splitting strongly in favour of staying, albeit with some difference in quite how strongly (ICM had 55% of Labour voters backing REMAIN, YouGov had 58%, ComRes 73%). The contrast among Tory voters was larger, ComRes has Tory voters wanting to stay, ICM has them broadly split, YouGov has them favouring exit: in the most recent polls YouGov had only 33% of current Tory voters wanting to stay, ICM had 42% of 2015 Tory voters, ComRes had 56% backing remaining. In practice, of course, how they Tory vote ends up splitting will depend to a significant extent on the leadership David Cameron gives in the referendum and which senior Tory figures come out in favour of leaving – there’s a long way to go yet.