A third of Britons have said that, were a referendum held tomorrow, they would vote to leave the European Union.
A poll by ComRes for the Daily Mail showed 33 per cent would leave, while 51 per cent would vote to remain part of the EU.
However, the poll also suggested a slight change in opinion when the question is whether the UK should remain a "member of the European Union" - the wording for the question the government proposed last week - where 58 per cent said yes, while 31 per cent said no.
Tom Mludzinski, head of political polling at ComRes, pointed out that the referendum will be won by "those who turn up".
"The 'Yes' Side is strongest among younger generations who are least likely to vote, but also among the more affluent who tend to turnoout.
"These key groups will be the ones to watch as the referendum draws closer. Building up support among those who are unlikely to vote, as Labour did, will ultimately end in failure. Targeting the regular voters is the key to success in this referendum."