In contrast, doubt about how the Brexit process has been handled does little to change minds, writes Sir John Curtice, Britain's leading polling expert

Perhaps unsurprisingly, there is now almost a consensus among voters, both Remain and Leave, that the UK government has made a mess of the Brexit process. NatCen has reported that 81% think that the UK government has been handling the process badly, twice the proportion at the beginning of the process. Most recently YouGov and ORB both put the figure even higher, at 87% and 89% respectively. Meanwhile, nearly two-thirds of voters think that the UK is heading for a bad deal.

Yet, headline grabbing though they may be, these perceptions have done little to persuade Leave voters that Brexit is a bad idea after all. Those Leave voters who now think that the UK is heading for a bad deal are just as likely as those who take a less pessimistic view to say that they would vote Leave again. The difficulties that have beset the delivery of Brexit are evidently not regarded as a reason to abandon its achievement.

However, there is a debate that has made a difference to voters’ views about the principle of leaving – that is, whether leaving the EU will be economically beneficial or damaging for the UK.

Although attitudes on this subject have not changed anything like as dramatically as in the case of perceptions of the Brexit process, there has been a perceptible increase in pessimism about the economic consequences of Brexit. Shortly after the referendum NatCen reported that 45% of all voters reckoned that the economy would be worse off; now that figure stands at 58%. Even though Leave voters are much less likely to share in this pessimism, the proportion who think it would be worse off has increased from 9% to 25%.

Many within this growing if still small group of economically pessimistic Leave voters have changed their minds. Only 46% say they would vote Leave again. In contrast, no less than 94% of those Leave voters who think that Brexit will make the UK economy better off would vote the same way again. It seems that a loss of confidence in the economic consequences of Brexit does influence some voters to think again about the merits of leaving the EU.

This has important implications for those campaigning for a second EU referendum in the hope and expectation that such a ballot would produce a different result. Although the polls consistently report a narrow lead for Remain (on average by 54% to 46%), much of this lead rests on the pro-Remain preferences of those who did not vote in 2016, and who perhaps might also fail to vote a second time around. To win any second ballot, those advocating that the UK should remain in the EU would need to fight a good campaign that bolstered and even increased support for that position

To do that, it looks as though arguments that Britain should remain in the EU because the last two years have shown just how difficult and troublesome it is to exit the EU will not have much impact. Rather, the Remain side would have to win more effectively than it did first time around the argument that being part of the EU is in Britain’s economic interests.

However, to win such an argument the Remain side would need to do more than focus on what it considers to be the negative economic consequences of leaving the EU, as it did in the 2016 referendum.

That such an approach was proving insufficient became apparent just ten days before the 2016 referendum in a poll conducted by YouGov for The Sunday Times. Like many other polls, it found that voters were inclined to the view that leaving the EU would be economically disadvantageous. However, this poll went on to ask voters what they thought would be the economic impact of remaining in the EU. This revealed that they were far from optimistic about such a prospect. Just 19% said that remaining in the EU would be beneficial for the economy, while, slightly more, 24% stated that it would be damaging.

Whatever doubts voters might have had about the economic consequences of leaving, there was evidently little sense that staying in the EU would actually be beneficial.

This should not surprise us. In contrast to the position when the UK first joined the Common Market in 1973, it is now more difficult to present the EU as unquestionably an economically successful institution. Forty years ago, it was possible to compare the relatively high economic growth rates of the six original members of the Common Market with Britain’s anaemic, ‘stop-go’ performance. In 2016, in contrast, the fallout from the 2008 financial crash in the form of a Eurozone crisis that had an adverse impact on the economies of much of southern Europe in particular cast a shadow over the EU’s reputation for financial prudence and economic success.

Any pro-Remain second referendum campaign will need to address that issue by arguing how the UK could use the semi-detached status that it enjoys within the EU (not least in not being part of the Eurozone) to deliver economic success – and, above all, rising living standards.

There are lessons here too for those on the Leave side of the argument. It appears that voters have not been convinced by the arguments during the last two years that leaving the EU would bring economic benefit by enabling the UK to free itself from EU regulation and strike free trade deals with the rest of the world.

Consequently, there appears to be a risk that leaving the EU may no longer represent a majority view. There are implications too for the deal that the UK should be seeking to secure in the event that the decision to Leave is eventually endorsed by Parliament and the UK and the EU embark on talks about their future relationship.

If a majority of voters are to be convinced that the new relationship represents a satisfactory resolution of the Brexit debate, they will need to be persuaded that, however ‘soft’ or ‘hard’ it might be, the relationship will enable the UK to prosper economically. Otherwise, the argument about Brexit is likely to continue for years to come.

John Curtice is Professor of Politics, Strathclyde University and Senior Research Fellow, NatCen Social Research and ‘The UK in a Changing Europe’ project.

This is an abridged version of a longer article to be published in the Summer 2019 edition of IPPR's Progressive Review magazine