The European Union faces so many different crises that it has been–until now–impossible to predict the precise catalyst for its likely demise. The obvious candidates for destroying the EU include the looming refugee crisis, the tottering banking structure that is resistant to both bail-outs and bail-ins, the public distrust of the political establishment, and the nearly immobilized EU institutions.

But the most immediate crisis that could spell the EU’s doom is Prime Minister David Cameron’s failure to wrest from Brussels concessions that he needs in order to placate the increasingly euro-skeptic British public. Prime Minster Cameron has failed because the EU cannot grant the necessary concessions. There are three special reasons, as well as one underlying reality, that have made Cameron’s task impossible.

First, a profound reform of the EU-British relationship, which Cameron initially promised, was always impossible, because it required a “treaty change” in each of the twenty-eight EU member-states. That could not happen without approval either by parliamentary votes or, as this is especially difficult, a national referendum that Brussels dreads. There is simply no appetite in Europe to run such risks just to appease the UK.

Second, Cameron was willing to settle for a compromise but failed to obtain most of what he needed, because Brussels fears that other member states will follow the British example and demand similar accommodations. That would result in a “smorgasbord EU” in which each country could pick and choose what serves its own best interests. In other words, it would make a mockery of “an ever closer Europe.”

And so, Cameron ended up with what one Conservative Member of Parliament, Jacob Rees-Mogg, called a “thin gruel [of a reform that] has been further watered down.”

To make matters worse, Cameron’s “thin gruel” will require a vote by the EU Parliament after the British referendum takes place. As a sovereign body, the EU Parliament will be able to make changes to any deal approved by the British public–an uncomfortable and inescapable fact that the advocates of “Brexit” will surely utilize to their advantage during the referendum campaign.

At the root of the conundrum faced by the British and European negotiators is a struggle between a national political system anchored in parliamentary supremacy and a supra-national technocracy in Brussels that requires pooling of national sovereignty in order to achieve a European federal union. The public debate over the referendum is driving this fundamental incompatibility home. The choice between one and the other can no longer be deferred.

The most common image of a failing Europe is that of something falling apart, unraveling, crumbling away, or even evaporating into thin air. This imagery is misleading. Following the British referendum, and perhaps even before it, the EU will most likely implode.

Once the odds of Britain’s exit from the EU increase from merely likely to near-certain, the rush for the exits will begin in earnest. It is impossible to predict which of the remaining member-states will lead the charge, but the floodgates are sure to open. Those pro-EU governments that still remain in office are under siege in almost every member-state. As in Britain, the establishment parties will have to appease increasingly hostile electorates by getting a “better deal” from the EU. Or they could face electoral oblivion.