On June 23, Britons will hold a referendum on whether to stay in or leave the European Union and surveys point to close vote. "Brexit" also would produce serious challenges for the United States, and possibly for Democratic presidential candidate Hillary Clinton. The EU represents much of what Republican candidate Donald Trump is campaigning against. So, a Brexit vote will give him an opening to lace his smack-downs of Clinton with talk on trade, immigration and NATO.
If Britons say "No" to Europe, the first fallout will hit when global investors pull back from Europe and Britain, driving down the euro against the dollar and, by 2017, driving up the U.S. trade imbalance with Britain and Europe. Britain has also been a big advocate of the Trans-Atlantic Trade and Investment Partnership, and Brexit could well disrupt those talks. Trump will call these developments proof that wide-ranging trade pacts don't work and that Clinton doesn't appreciate how they weaken countries.
In fact, wide-ranging trade deals have been key factors in Europe's recovery in the 1960s and '70s, the developing world's rapid modernization since the early 1990s and America's leadership in information and internet technologies.