For the first time, the Prime Minister will include discussions on Europe at a meeting of the Cabinet sub-committee on which leading Liberal Democrats are represented.
The move towards a Lib-Lab partnership on Europe will aim to capitalise on the latest Conservative resignation which plunged Tories back into bitter recrimination over Europe.
Mr Curry, the party's agriculture spokesman and a leading supporter of the ex-Chancellor Kenneth Clarke, resigned attacking the Tories' intention to oppose the single currency at the next election. The stance, he said, "risks leaving us marooned by events, marginalised in debate, and alienated from sections of the electorate who would normally look to us as their instinctive home".
His was the second resignation from the front bench in a week which has also seen criticism of Mr Hague's European policy from three ex-Cabinet ministers, Michael Heseltine, Kenneth Clarke and Lord Hurd.
An exchange of letters followed a phone conversation between Mr Curry and Mr Hague at 9.30 yesterday morning. The Conservative leader remained unrepentant, releasing a letter which will have left pro-Europeans in no doubt about his determination to oppose EMU, and almost challenged them to quit the party.
The opposition leader said: "I believe it is more important to have this clear and pragmatic policy on the greatest issue of our day than to try to please everybody at the same time. Nothing will deflect me from promoting the policy on which we have agreed and in which I believe.
"I would rather fight for what I believe without the support of some members of the party than pretend we have no beliefs at all."
Mr Hague moved swiftly last night appointing the former agriculture minister, Michael Jack, as Mr Curry's sucessor.
Behind the scenes there was a bitter row as Hague supporters accused pro-Europeans of leading an orchestrated programme of "rolling resignations". Euro-sceptics believe a campaign of defections is being orchestrated by Michael Heseltine, the former Deputy Prime Minister, and Kenneth Clarke, the ex-Chancellor.
One pro-Hague source claimed Messrs Clarke and Curry had been seen on Monday talking to Ian Taylor, spokesman on Northern Ireland, who resigned his post two days later. The allegation of co-ordination was denied by Mr Curry.
Some Hague allies predict that turbulence over Europe is over, others foresee a phased rebellion which, they believe, would marginalise those involved.
The party's pro-Europeans face another test this week when Conservative business managers decide whether to impose a three-line whip over the Amsterdam Treaty, to be debated a week tomorrow. Collective responsibility is likely to be enforced. One pro-European said: "Central Office is not in control of events. People now know that, if they have had enough and want to go, they will not be alone."
Mr Blair moved to shore up plans for consensus on Europe. Tuesday's meeting of the Cabinet sub-committee, which includes Liberal Democrats, will, for the first time, discuss Europe.
Paddy Ashdown, Liberal Democrat leader, will be among senior party figures who will hear a report from Robin Cook, Foreign Secretary, on Britain's presidency of the European Commission. Mr Blair will attend the meeting, which is expected to discuss the single currency.
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