Therese Raphael identifies what makes broad support for the Leave campaign in the U.K. so remarkable:

What makes the forecasted “leave” vote so dramatic is that nearly every official body, national and international, has lined up the other way. Britain’s political parties (with the exception of the anti-immigrant UKIP party) and the country’s trade unions (which opposed remaining in Europe in Britain’s 1975 referendum) have backed remaining in the EU. Large businesses, small businesses and the scientific and tech communities all broadly want to remain in Europe. Former NATO chiefs, the U.S. president and other world leaders have also pleaded with Brits to stick around.

It might be too simple to say that support for Leave has been growing because “nearly every official body, national and international, has lined up the other way,” but it seems clear that most of the people likely to vote in the referendum don’t put much stock in what these leaders have to say. Insofar as the interventions of outside governments have had any effect on the debate, they seem to have driven people away from the Remain side. Perhaps this is simply a predictable reaction to having foreign governments tell you what is best for your country, or perhaps it reflects how little confidence these voters have in the judgment of the Obamas and Merkels of the world. The lopsided elite backing for Remain has been practically begging for repudiation by voters, and that repudiation is looking more likely than it did a few months ago.

When European Council President Donald Tusk absurdly declares that “Brexit” might eventually lead to the destruction of Western civilization, I have to assume most sane people instinctively recoil from his side of the debate. The problem with these over-the-top warnings isn’t just that they’re obviously false and ridiculous, but that they show that their side cannot make a case in favor of staying in the EU that isn’t framed in apocalyptic terms. No one feels any attachment or loyalty to the EU, and so there is no positive emotional or patriotic appeal that can be made for it, and I suspect that is another major reason why the vote appears set to go against it next week.