The European question is the grim reaper of British politics – dividing parties, debilitating governments, and destroying careers. But never before have the stakes surrounding the question been so high. Prime Minister David Cameron’s decision to hold a referendum – perhaps as early as June – on the United Kingdom’s continued membership in the European Union could bring down his government, destroy his political party, and literally tear his country apart.

Cameron is doing all he can to renegotiate the terms of membership in order to persuade voters to choose to remain in the EU. But referendums are notoriously unpredictable. And there is no reason to believe that the storms of populism blowing across the continent will not make landfall in the UK.

A decision to leave the EU would fall like a sledgehammer on the British economy and greatly diminish its international stature. Far worse, it could lead to the dissolution of the UK. The Scottish National Party has threatened to hold a second independence referendum if British voters decide to leave the EU. This, the SNP’s leaders argue, would allow an independent Scotland to remain part of Europe, even as England, Wales, and Northern Ireland set out on their own.

Were this to happen, the dismemberment of the UK would make Cameron’s legacy the worst of any prime minister in British history. That might seem like a high bar, given that the title is usually associated with Neville Chamberlain, who famously tried to appease Adolf Hitler. But while the stakes were certainly higher in Chamberlain’s case, at least his polices could be reversed before they destroyed the country (and Winston Churchill did just that). If Cameron loses both the EU and Scottish referendums, his successors will not be able to put the EU or the UK back together again.

As Cameron fights to save his party and his country, a line from Oscar Wilde resonates: “For each man kills the thing he loves.” The prime minister’s predicament is that his political strength depends on his ability to stretch the Conservative Party’s blanket over its uneasy bedfellows of flag-waving nationalists and free-market fundamentalists; but the European question pits one side against the other.

For capital and big business, EU membership is an economic imperative, offering access to 500 million consumers and reserves of cheap, qualified labor. For nationalists, it is a threat, undermining British sovereignty and control over the country’s borders. Cameron’s call for a referendum, first issued when he was in opposition, was an attempt to appease both sides, allowing each to stick to their principles while promising to give voters the final say. The trouble began when he became Prime Minister and was forced to pick a side.

Fortunately for Cameron, he has a lot going in his favor. The facts are clear: the UK’s economy, security, and international stature all benefit from EU membership. And broadly, the business community, trade unions, parliament, the media, and even a plurality of the British public all favor remaining in the EU. Meanwhile, opponents of EU membership have yet to make the case for a credible alternative.

Moreover, Cameron has an impressive track record of exceeding expectations. Few predicted he would take control of his party when he launched his leadership campaign in 2005. When the Conservatives came to power in 2010, many doubted that he would serve a full term as Prime Minister. And even Cameron himself did not expect to win an outright majority in last year’s general election.

But there is no guarantee that his winning streak will continue. The news from Europe has been unrelentingly grim, and it could ultimately sway the result of the referendum. The refugee crisis, terrorist attacks, and the lingering effects of the global economic crisis are all providing fuel for simmering nativist sentiment.

Worries over migration and the spectacle of a divided, dysfunctional Europe have benefited xenophobes and extremists across the continent. And terrorist attacks, by their very nature, are intended to provoke irrational backlashes (as evidenced by a recent referendum in Denmark, in which voters unexpectedly rejected a proposal to modify the country’s opt-outs from certain EU home-affairs regulations).

Cameron’s allies say he has only two modes of operation: complacency and panic. So far, he has faced his referendum challenge calmly. But that is likely to change as the vote approaches and the risk grows that he will be remembered as the leader who, to paraphrase Churchill, was given a choice between his party and his country, chose his party, and ended up losing both.

© Project Syndicate