To U.S. voters who have witnessed the rise of Donald Trump, the campaign urging Britain to abandon the European Union may appear eerily familiar.

There's the nationalism, the romanticized nostalgia for an earlier time, the mistrust of political and financial elites, and the fears that migrants are bringing crime and stealing jobs. Call it Trumpism minus Trump, the New York real estate developer who has emerged as the presumptive Republican presidential nominee in the 2016 U.S. elections.

If British citizens vote on Thursday in favor of exiting the European Union, it would allow Britain to negotiate its own trade deals and better control who enters the country, among other things. Both sides in the polarized debate have mounted extensive campaigns and polls show the vote could be close.