Messy and poisonous though it already is, Britain's 26-to-one row with the European Union could become nastier and more bewildering.
EU officials say that the Government has to make a critical choice in the next few days.
British Prime Minister David Cameron could reach out to his EU partners and risk howls of "u-turn" from anti-European backbenchers and the Eurosceptic press.
Alternatively, he could ratchet up his row with the other 26 by opposing the use of EU institutions to implement the "inter-governmental" plans for closer fiscal union agreed in Brussels last week. This could undermine already fragile market confidence in the credibility of a legally vague agreement and help to propel the euro over a cliff.
A collapse of the euro, blamed rightly or wrongly on British "dog-in-the-manger stubbornness", would make the present row "look like a passing cloud on a summer's day", one EU diplomatic source said yesterday. Despite mixed signals in Cameron's statements to the House of Commons, Brussels officials believe the British PM - under pressure from his Liberal Democrat Coalition allies and from the Foreign Office - is now ready to take some of the heat out his dispute.