Phone and online polls show support for Brexit growing to 53%, with proportion backing remain campaign falling to 47%

Support for leaving the EU is strengthening, with phone and online surveys reporting a six-point lead, according to a pair of Guardian/ICM polls.

Leave now enjoys a 53%-47% advantage once “don’t knows” are excluded, according to research conducted over the weekend, compared with a 52%-48% split reported by ICM a fortnight ago.

The figures will make grim reading for David Cameron, George Osborne and the Labour party. They follow a fortnight in which immigration became the dominant issue in the referendum campaign, with the publication of official figures showing that net migration had risen to a near-record 333,000 in 2015.

Prof John Curtice of Strathclyde University, who analyses available referendum polling data on his website whatukthinks.org, noted that after the ICM data, the running average “poll of polls” would stand at 52% for leave and 48% for remain, the first time leave has been in such a strong position.

“These results are consistent with the generality of numbers over the last couple of weeks, in which there has been some weakening in the remain position,” he said. “It was already plain that this race was far closer than the prime minister intended and he must now be feeling discomfort at the thought that the outcome really could be in doubt.”

Throughout the long campaign, internet surveys have pointed to a close race. But the remain camp had been able to take heart from more traditional telephone polls, which have tended to show them enjoying a double-digit lead.

That appears to have changed recently. Two weeks ago, ICM reported for the first time that leave had taken the lead in one of its phone polls.

Under the surface, the proportion of voters who remain undecided is dwindling, in possible evidence of the hardening of attitudes towards EU membership.

In ICM’s telephone fieldwork in particular, 13% of respondents were indicating uncertainty about how they would vote a fortnight ago, but that figure has now fallen to 6%. Online, 7% say they don’t know, down from 9% two weeks ago.



There are also signs that Conservative infighting, which has characterised the referendum campaign, is now hurting the party in the Westminster stakes. The Tories are down two points on the month in the long-running Guardian/ICM telephone poll series, at 34%, only one point ahead of Jeremy Corbyn’s Labour party, which gains one on the month to reach 33%.

However, the referendum is not producing a sustained Ukip surge: Nigel Farage’s party sinks by one point from the previous poll, to 14%. The Liberal Democrats climb two to 9% and the Greens also pick up two, reaching 5%. The Scottish National party and Plaid Cymru remain on 4% and 1% respectively. Other minor parties are unchanged at 1%.

In its experimental online voting intention series, ICM puts the Conservatives ahead on 34%, Labour on 30%, Ukip on 19%, the Lib Dems on 8%, with the SNP and the Greens both on 4%, and assorted others with 1%.

The mood at Westminster has recently turned, especially bleak among Labour MPs concerned that the party’s arguments for remaining in Europe are not connecting with its voters. The latest telephone poll suggests that remain is still the preferred choice of Labour voters, by 58% to 38%.

However, this balance is not sufficiently emphatic to overpower the combination of a slight 49%-47% margin for leave among the Tories, and a crushing 97% to 2% preference for leave among Ukip supporters.



Breaking down the population between generations confirms that Eurosceptism sets in with age: among the young, aged 18 to 34, the balance is 56% to 39% for remain, whereas pensioners of 65 and over lean the other way, by 55% to 39%.

Voters in professional “AB” grade occupations are strongly in favour of staying in Europe (57%-38%), whereas skilled manual workers (C2s) are plumping for leave by an emphatic 67% to 29% margin.

ICM Unlimited interviewed a random sample of 1,000 adults by telephone between 10 and 13 June 2016. ICM separately interviewed 2,001 adults aged 18 and over online between 10 and 13 June 2016. In both cases, interviews were conducted across the country and the results have been weighted to the profile of all adults. ICM is a member of the British Polling Council and abides by its rules.

• This article was amended on 14 June 2016 to correct the name of the website whatukthinks.org.