David Cameron must go out and make the case for Britain's continued membership of the European Union, one of the grandees of the Conservative Party has warned.
Lord Howe of Aberavon, who served as chancellor and foreign secretary in Margaret Thatcher's government, said the Prime Minister had made his position more difficult by his "repeated concessions" to the Eurosceptics.
He said that Mr Cameron now must give a lead on the issue, and not leave it to outside individuals and organisations - from US president Barack Obama to the CBI.
Mr Cameron is currently committed to renegotiating the terms of Britain's membership and then putting the outcome to a vote in an in/out referendum after the next general election if the Conservatives win power.
But while the Prime Minister has said he wants Britain to remain in the EU, Lord Howe - whose resignation over Europe in 1990 triggered Baroness Thatcher's downfall as prime minister - said that it was not enough.
In a statement released by the pro-EU British Influence campaign, Lord Howe said: "The more people understand and experience the reality of Britain's place in today's interdependent world - an interdependence which Conservative policies in the 1980s did so much to promote - the less likely they are to want this country to leave the European Union.
"Sadly, by repeated concessions to the Eurosceptics, the Government made its own position on Europe, and in Europe, more difficult. Now the Prime Minister and his ministers need to make the case for membership strongly and clearly, rather than just leaving it to President Obama, Nissan and the CBI - powerful advocates as these may be."
At the same time, British Influence released a YouGov poll of more than 700 "opinion formers" showing 69% believed Britain should stay in the EU as against 23% who wanted to leave. Of those who want to remain in, 81% thought the Government was not doing enough to make the case.
British Influence director Peter Wilding said: "Overall, the results show the value placed in Britain's relationship with the EU amongst opinion formers in Britain today, but more work needs to be done."
:: YouGov questioned 708 members of its opinion formers panel - a panel of more than 4,000 leading figures from UK politics, business, the media, arts and culture, charities and academia - between December 12 and 20.