Revealed: Two thirds of British voters are Eurosceptics – but they aren't convinced we should leave

Now that the referendum date is known and the campaign under way, both Remain and Leave campaigners are fine-tuning their appeals to voters.

But on what should they focus? Arguments about how membership threatens Britain’s identity and sovereignty? Claims that staying the EU would make it impossible to get immigration down? Suggestions that Britain would lose influence in the world if it left the EU? Or evidence of how the economy would suffer in the wake of a Brexit?

Now, for the first time, someone has looked systematically at this question – at the level of support for all of the key arguments in the referendum campaign and what impact they have on voters’ attitudes towards Europe. Research published on Wednesday from NatCen's British Social Attitudes surveyshows that all of these claims are in fact quite popular.

Unlike the opinion polls, which are conducted in a matter of days, interviewing for British Social Attitudes survey is done over an extended period of four months. The advantage of this approach for getting an accurate guide to where public stands is demonstrated by the fact that how participants in the survey said they voted in last year’s general election closely matches the actual election result.

According to the survey, nearly half of us (47 per cent) think that Britain’s distinctive identity is being undermined by the country’s membership of the EU. Well over half (57 per cent) reckon that immigration would be lower if we left.

Yet equally, 36 per cent believe our influence in the world would be diminished if we left the EU, while 40 per cent fear the economy would be worse off.

Evidently, both Leave and Remain have arguments that resonate quite widely with the public. But if it is to be an effective weapon in the campaign, a claim needs not only to be popular, but also regarded by voters as a good enough reason to vote in one direction or the other.

When we take that consideration into account it is clear that it is arguments about the economic consequences of remaining and leaving that are likely to prove the most persuasive.

People’s attitudes towards the EU are not simply binary – either enthusiastic to remain or keen to leave. Many find themselves somewhere in between – sceptical about the EU, but not sure they want to leave the club.

Indeed, no less than 65 per cent of voters are essentially Eurosceptics: they either say they want to leave or, more commonly, they think Britain should remain in the EU but try to reduce its powers. This, of course, is precisely the kind of voter to whom David Cameron has been trying to appeal through his renegotiation of Britain’s terms of EU membership.

But when asked whether they want Britain to continue to be a member of the EU or whether it should withdraw, only 30 per cent opt for "withdraw", less than half the proportion who emerge as "sceptics". Twice as many, 60 per cent, say "continue".

In short, scepticism about the EU is far more widespread than is the inclination to leave. This is because voters are only likely to back leaving if a concern about issues such as identity, sovereignty and immigration – that is, the concern on which above all scepticism feeds – is coupled with the much less popular belief that Britain’s economy would be better off if it left the EU.

Consider, first of all, those voters who think that membership of the EU is undermining Britain’s distinctive identity, but who are not convinced that Britain’s economy would be better off under independence. Only a minority (40 per cent) of this group want Britain to withdraw from the EU.

Then look at the level of support for withdrawing amongst those who are not only concerned about Britain’s identity, but also believe that the country’s economy would be better off if we left. No less than 82 per cent of this group back Brexit.

At the moment the first of these two groups is considerably larger than the second. If it is to win the referendum, the Leave campaign needs to convince more voters of the economic benefits of leaving.

Equally, the key task facing the Remain campaign will be to persuade a sceptical nation that David Cameron has addressed enough of their concerns about Brussels’ influence through his renegotiation that the price of staying in the EU is still worth paying.

Neither of these tasks looks like it will be an easy one. But ultimately it will be what voters make of their respective economic arguments that is likely to determine which side’s efforts reap the greatest rewards.

• A YouGov poll for The Times has found that 38% of people want to leave the EU, 37% stay in it and 25% are either undecided or not planning to vote.

John Curtice is Senior Research Fellow at NatCen Social Research and the UK in a Changing Europe programme. For further details, click here.