The No campaign, the main group campaigning against British participation in the euro, is preparing to distance itself from attempts by the Conservative Party to make the single currency a key general election issue.

Strategists for the campaign say they think the Conservatives are facing defeat and are determined that the broader anti-euro coalition should not be dragged down with them.

Mr Dominic Cummings, campaign director of Business for Sterling, which set up the No campaign with Lord Owen's New Europe group, said the campaign would prefer to stay out of the election altogether. The groups will say that they will not endorse the views of any political party, or allow themselves to be drawn into the election. In a further set-back for the Conservatives, Mr Paul Sykes, the millionaire Eurosceptic who has hinted at large sums for the Tories if they toughen their euro policy, said he would not give the Tories any cash after all.

"I had a quick, short meeting and we just couldn't hit it off. There was a difference of opinion. I believe Conservatism and a Conservative should never set a date in the future for giving up control of one's economy - that wasn't compatible with me supporting the party," Mr Sykes told BBC's On the Record programme.