Polls Open In Britain's Historic EU Referendum

Britain's Prime Minister David Cameron, foreground, addresses Vote Remain supporters with former Prime Minister John Major, right, during a rally in Bristol, England Wednesday June 22, 2016. On Thursday Britain goes to the polls in a referendum on whether to remain or leave the EU. (Geoff Caddick/PA via AP) UNITED KINGDOM 

Polls opened in Britain Thursday for a referendum on whether the country should quit the European Union bloc of which it has been a member for 43 years.

Associated Press report continues:

More than 46 million people are registered for the vote, which asks: "Should the United Kingdom remain a member of the European Union or leave the European Union?"

Polls are open until 10 p.m. (2100GMT), with results due early Friday.

The referendum has exposed deep divisions over issues including sovereignty and national identity.

"Leave" campaigners claim that only a British exit can restore power to Parliament and control immigration. The "remain" campaign led by Prime Minister David Cameron argues that Britain is safer and richer inside the 28-nation EU.

Financial markets have been volatile ahead of the vote, with opinion polls suggesting a tight race.

Advocate to exit Europe Boris Johnson poses for a selfie photo with voters during a whistle stop tour of the country on the final day of campaigning before Thursday's EU referendum vote, in Selby, north England, Wednesday June 22, 2016. On Thursday Britain votes in a national referendum on whether to stay inside the EU, a momentous decision with far-reaching implications for Britain and Europe. (Andrew Parsons / PA via AP) UNITED KINGDOM 

Turnout is considered critical in the vote, as polling suggested there were a number of undecided voters. Those who waver at the end tend to go for the status quo, which would favor the "remain" campaign.

It was raining heavily in some parts of the country, which could have an effect on turnout. Downpours and flooding swamped parts of London and southeastern Britain. London's Fire Brigade received hundreds of calls of weather-related incidents early Thursday, including some reports of flooding and lighting strikes.