David Cameron's pledge of an in/out referendum on EU membership if the Tories win the next general election appears to have secured the party a significant boost in the polls.
A survey conducted in the wake of the Prime Minister's long-awaited speech on Wednesday showed a five-point Conservative jump on last month - mostly at the expense of Ukip - halving Labour's lead to six.
Mr Cameron insists he wants to stay in the EU but pledged to renegotiate the relationship to claw back powers and offer voters a choice of that deal or exit by the end of 2017 if the Conservatives are returned to power in 2015.
His pledge came amid intense pressure from eurosceptic backbenchers concerned about the threat posed by a resurgent UK Independence Party but has been attacked by Labour and his Liberal Democrat coalition partners.
The poll, by ComRes for the Sunday Mirror and the Independent on Sunday, put the Tories on 33%, with Labour stood still at 39% and the Liberal Democrats up two at 11%. Ukip, which has registered significant advances in recent months, fell back four points to 10%.
The poll found a majority of voters backed Labour and Lib Dem warnings that Mr Cameron's position would cause "years of uncertainty which will be bad for the British economy" by 43% to 30%. But a majority also now believe that leaving the EU would in itself be bad for the economy in terms of lost jobs and trade - by 38% to 36%, a turnaround from November when 40% disagreed and 36% agreed.
Mr Cameron enjoys the confidence of 42% of voters that he is "good at standing up for Britain's interests in the European Union" while only 22% said they believed Labour leader Ed Miliband would be if he became prime minister.
And though the Tory leader he still has an overall negative personal rating as premier - by 32% to 46% - it has significantly improved since the 27% to 51% gap of last month and is his best since June 2011.
The poll was released as Mr Miliband - who has said the party is not in favour of the referendum promised by the Prime Minister - faced renewed calls from within his own party for an immediate in/out referendum.
Former Europe minister Keith Vaz, a supporter of EU membership, told the Sunday Mirror it was "time to settle the question of Britain's membership in the EU once and for all". And ex-PM Tony Blair used an article in the Mail on Sunday to issue a rallying cry to the "sensible, solid majority" in favour of membership to start campaigning hard for a "yes" vote.