Britain went to the polls on Thursday, with the future of Brexit hanging in the balance, in a snap pre-Christmas election aimed at drawing a line under years of political gridlock and bitter division.

More than 4,000 polling venues across England, Scotland, Wales and Northern Ireland — including a windmill, some pubs and a chip shop — opened their doors for a poll described as the most important in a generation.

A decisive victory for Prime Minister Boris Johnson would most likely end Britain's 46-year involvement in the European Union next month, setting Britain on course to chart a new future based on closer ties with the United States and even China.

But a win for the pro-EU opposition could still reverse the Brexit process and give Britain its most leftist government in decades led by veteran socialist Jeremy Corbyn, committed to re-nationalisation and massive public sector spending.

"For them. Vote Labour," the pro-Corbyn Daily Mirror said on its front page, showing pictures of the homeless sleeping on the street and nurses in understaffed hospitals.

"Save Brexit. Save Britain," the pro-Johnson Sun newspaper countered on its own front page.

Johnson himself said the election was on a "knife edge" with the polls indicating him in the lead, but possibly by a margin too small to form his own government.

Johnson hopes to secure majority

Up for grabs are all 650 seats in the British parliament, which has been deadlocked since the 2016 referendum on EU membership that saw a majority vote to leave.

Prime Minister Boris Johnson, who took over from Theresa May in July after she was unable to get parliament to approve her EU divorce deal, is hoping to secure both a mandate and a majority.

"Just imagine how wonderful it will be to settle down to a turkey dinner this Christmas with Brexit decided," he said in a final message to voters.

The first indication of the overall result will come in an exit poll at 2200 GMT. The first actual result is due from around 2300 GMT. The remainder will trickle in overnight.

Crossroads

Looking to stop Johnson is the main opposition Labour party.

Victory would make its 70-year-old leader Jeremy Corbyn the first Labour prime minister since Gordon Brown in 2010 and the oldest first-time premier since Viscount Palmerston in 1855.

Corbyn is proposing to renegotiate softer exit terms with Brussels within three months and put them to a new referendum, alongside an option to remain in the 27-member bloc, after a three-month campaign.

A franchise extension would enable millions of EU nationals in Britain to vote in the referendum.

Corbyn said Britain was at a crossroads and the election was "truly historic".

"Vote for hope. Vote for real change," he said.

The election features 3,321 candidates — from 18-year-olds to octogenarians — in constituencies covering windswept Shetland off northeast Scotland, to the Isles of Scilly more than 1,200 kilometers away off Cornwall, in southwest England.

Johnson has hammered home his message to "Get Brexit Done" against a backdrop of voter fatigue at the election — the third in less than five years — and the tortuous Brexit process.

But the EU itself has indicated the chances of securing a comprehensive trade deal before a December 2020 deadline is unrealistic.

That would again raise the prospect of Britain facing a "no deal" scenario, plunging business and the British economy into fresh uncertainty.

Corbyn, meanwhile, has had to brush off claims of indecision about his neutral Brexit stance, and claims of anti-Semitism within Labour.

Questions have also been asked about the cost for his radical leftist programme for massive public sector investment and renationalisation of some key sectors.

He has positioned Labour as the only defender of the UK's cherished state healthcare system that he alleges Johnson wants to sell off in a "toxic" post-Brexit trade deal with US President Donald Trump.