The Fight to Keep Britain in the EU Just Got a Lot Harder

Not quite a year ago, British Prime Minister David Cameron achieved the impossible and won a majority in Parliament. It’s a small majority, but the internal battles of the Labour opposition have left the impression that Cameron is dominant in British politics. So it’s surprising that he might have to resign in June. If he does, he’ll have been forced out not by a rival or by a scandal, but by the misfiring of a three-year-old gambit of his own making.

Europe has been the issue that’s caused the Tories the most difficulty ever since a fight over the extent of British integration into the European Union helped bring about the fall of Margaret Thatcher in 1990. Successive leaders were either chosen for their purity on the issue—less Europe, which was Thatcher’s stance—or undermined for their lack of it. By 2005, when Cameron took the job, it was impossible to be elected leader without making at least some noise about distancing Britain from the EU.