Among the headlines here last weekend was one that trumpeted: “Cameron to Defy EU on Migrants. ” This suggested that the prime minister intends to make it much harder for Romanians and Bulgarians to claim British welfare benefits.Such an initiative would run contrary to E.U. law and assuredly meet a challenge in the European Court, which would probably rule against the British government. But a political imperative presses upon Prime Minister David Cameron. With just 18 months before a general election, he faces a threat of mass defections from his own Conservatives to the fringe UK Independence Party, committed to contrive Britain’s departure from the European Union. To frustrate UKIP - Britain’s Tea Party - the Tories must show voters that the coalition government in which they are dominant partners can contest perceived EU intrusion on British rights, national interests and discretionary powers. Most of the business community considers that quitting the European Union would be an economic disaster. UKIP and the Tory right insist that easy trading arrangements would remain available outside the Union because Britain is a big market for European goods. But diplomats and bankers argue that if Britain goes it alone the other member states would concede it no favors. Most single market trading arrangements would survive, but Britain would lose its voice in future rules affecting exports. Scarcely any individual or organization in Britain today, however, is making the pro-Europe case with conviction. Ministers say as little as possible about it, to avoid fueling isolationist hysteria, and thus the EU’s critics shoot at an open goal. Membership has never been less popular. It is no great exaggeration to say that many British people, especially the elderly, believe that breaking with Brussels would deliver instant improvements in the weather and the England football team. Ten months ago, Mr. Cameron made a speech in which he declared his belief that while EU membership is positive for Britain it has shortcomings: gratuitous bureaucratic and regulatory intervention by Brussels in matters properly addressed by the British Parliament; an extravagant welfare culture; a chasm between many EU policies and the wishes of member peoples, not least in the matter of unrestricted internal immigration. Mr. Cameron asserted that the institution must become much more flexible to accommodate the differing aspirations as well as the social and economic circumstances of its 28 members. He acknowledged the EU’s unpopularity among his compatriots, saying, “Public disillusionment with the EU is at an all-time high” and people “wonder what the point of it all is.” The speech was widely applauded as a proclamation of British grievances. Mr. Cameron concluded by declaring that, while his country should remain in the Union, it should not do so on any terms; there must be a renegotiation. Since then, the British government has strived to forge alliances to further this objective. The Germans, led by Chancellor Angela Merkel, are most anxious for the British to stay - and recognize the danger that it will go. They also share British frustrations about the manner in which the European Commission conducts its affairs, apparently heedless of cost to richer member states. But there are few signs that the EU nations are anywhere near ready to support Mr. Cameron in securing renegotiation of British membership terms. The priority of most governments is to preserve the euro zone, of which Britain is not a member. The condition of Europe’s currency looks less desperate than this time last year. But basic problems persist, about unacknowledged and irretrievable debt, the fragility of many European banks, and the grim economic conditions in southern European states. Until a credible path is identified for the euro’s future, members show scant interest in addressing Britain’s demands. A central banker told me early last year that he believed Mr. Cameron made a big mistake by promising British voters an in/out referendum on Europe in 2017, because it seemed unlikely that the euro’s fate would be resolved by then; thus, Britain’s electorate could not be offered a clear vision of what sort of Europe they might remain in, or abandon. This still seems so. The euro zone drama has been ongoing for so long that many pundits have ceased to use the word “crisis” because that implies an imminent denouement. But the scope for disaster remains considerable. The most important issues are those of whether a common currency is sustainable without political union; and whether, if the euro zone nations follow that path, Britain can remain the member of a “second tier,” bound by decisions that it would be unable to influence. If Germany and its allies advance toward political integration, it is unlikely the British will stay on the ship’s passenger list. At an Anglo-German conference a couple of years ago, I pressed the German delegates about whether they believed Britain would remain an EU member in, say, 10 years. Most expressed doubt, because they anticipated that a march toward political union would continue, even though polls emphasize many German voters’ hostility. The huge diplomatic challenge facing the British government is to persuade Europeans that a policy of general, rather than UK-specific, reform is vital to the Union’s future. Britain’s electorate will only be persuaded to continue membership if their government is able to offer it a less-Europe option; if the prospect is of more of the same, or even of a more intrusive and oppressive EU regime, then our commitment will become domestically unsustainable. This would be a great pity. I am a lifelong pro-European who in recent times has reluctantly come to believe, like many others, that the European project has gone horribly wrong. But I remember a German industrialist declaring at the aforementioned Anglo-German conference: “We all hope very much that your country will remain an EU member. But I would like to say, with the utmost politeness to our British friends, that should you leave, you are likely to find it cold out there alone.” That is why many of us are dismayed by the prospect of an in/out European choice being forced upon us. Britain’s “Quit Europe” campaign has gained a political momentum that will be hard to check, even if a pro-Europe Labour government gains power in the 2015 general election. The British have never shared the emotional attachment to the EU that inspires much of Europe’s elite, and today no politician is making the argument for membership with anything like the authority and passion that are necessary to turn the tide of public opinion.