05/06/2015 00:01 BST | Updated 04/06/2016 06:12 BST

Most Still Undecided On Referendum

The referendum on Britain's EU membership remains wide open, with fewer than a third of voters having firmly made up their mind which way to vote - and seven out of 10 remaining open to persuasion, according to a new poll.

But the survey of almost 4,000 voters for thinktank British Future suggested that some of the most passionate advocates of the In and Out causes might actually put off more people than they persuade.

Almost six out of 10 (59%) of those questioned by pollsters Survation said that they distrusted europhile former prime minister Tony Blair when he speaks about the EU, while 56% said they did not trust Ukip leader Nigel Farage on the issue. Just 28% said they trusted Blair and 36% Farage on the issue.

British Future director Sunder Katwala said the poll suggested that the In and Out campaigns should be wary of giving a prominent role to those keenest to lead them. 

Mr Farage, in particular, "appeals to existing supporters but repels the majority of British citizens who remain undecided about Britain's place in Europe", said the thinktank.

The survey found that Mr Blair - who intervened in the recent general election campaign with a speech warning of the dangers of sleepwalking into "Brexit" -  is distrusted by the public whether they are 'in' or 'out', 'decided' or 'undecided' alike.

Some 49% said they trusted Prime Minister David Cameron on the EU, against 41% who did not. European Commission president  Jean-Claude Juncker polled badly, distrusted by 51% of the public and trusted by only a quarter (25%).

Just 16% of those questioned said they were definitely in favour of staying in the EU and 12% definitely in favour of leaving. More than half (59%) said they were "leaning" in one direction or the other - 31% towards staying and 28% towards leaving - but would want to know the final conditions of any deal struck by Mr Cameron with Brussels before making their minds up.

Another 13% said they did not know which way they would vote.

Mr Katwala said: "The EU referendum is wide open. With seven out of 10 people wanting to hear more before they make up their minds - the 'Don't Knows' and the 'Leaners' will decide whether Britain stays in Europe.

"Either side could win this referendum. Their problem is that the most prominent and passionate voices could help them to lose.

"Both Nigel Farage and Tony Blair appear to be rather more likely to harm their cause than to help it, when preaching beyond the already converted.

"This research suggests that both sides of the referendum campaign might want to be wary of those who are keenest to lead the charge for them."

:: Survation questioned 3,977 adults online across Great Britain from May 8-14.