Britain's minority Conservative government has given up trying to get its Brexit deal through parliament and has called a snap election for 12 December. Here's why it will be an election like no other.
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The most volatile election
As the parties draw up their manifestos promising things like a better economy, employment and housing, one issue will dominate: Brexit. Despite the 2016 referendum's 52-48% vote in favour of leaving the European Union, the country is still a member of the 28-country bloc. The issue has divided the nation - and not along traditional party lines, helping make the 12 December election the most unpredictable in the UK's living memory.
An Ipsos MORI poll ahead of the election campaign put the ruling Conservatives on 41% with the main opposition Labour Party on 24%. But at the last two general elections - in 2015 and 2017 - half of British voters changed their party allegiance, according to research body the British Election Study.
Conservative Prime Minister Boris Johnson, who led the successful 'Leave' campaign in the 2016 referendum, hopes to win votes from the main opposition Labour party in working-class areas that voted to leave the EU.
Labour has said it would hold a second referendum, making it possible that the UK could cancel Brexit if it comes to power - something that Leave voters would want to avoid.
But those 'Brexiteers' might be lured away by the Brexit Party - which was set up in April by Nigel Farage to push for a 'clean' break from the EU - without a deal to keep the UK in line with EU rules.
Unless Farage and Johnson form some kind of alliance, the Brexit Party is likely to split the pro-Brexit. In the UK's first-past-the-post system, that could be very damaging for the Conservatives.
Johnson won the leadership of the Conservative party - and the prime ministership - with an unequivocal promise to deliver Brexit on 31 October. While he still styles himself as the leader who can deliver Brexit, his failure to do so so far might weaken his case.
"Johnson’s slogan, 'Get Brexit Done', feels like an appealing message to a public weary of months of knife-edge votes and reverses," writes Bloomberg journalist Robert Hutton. "But it’s also an admission that this government has had a single project since 2016, has failed to deliver on it, and everyone is sick of waiting,"
On the other end of the Brexit spectrum, the Liberal Democrats and Scottish Nationalists are campaigning to keep the UK in the EU with a less ambiguous message than Labour's. They could also split the vote, this time to the detriment of Labour.
Johnson called the snap election after it became clear parliament would not back his version of Brexit by 31 October. The new Brexit deadline is the end of January. That means the election will be held in winter - something that has not happened since 1923. It remains to be seen what impact the dark, chilly evenings will have on turnout or how voter sentiment might be affected.
With healthcare one of the top political issues, a winter health crisis could play badly for the Conservatives. Labour, which created the National Health Service after World War Two, hopes voters won't believe Johnson's promises to invest in the NHS. Labour leader Jeremy Corbyn told his supporters that a future Conservative government would use a post-Brexit trade deal with the US to sell off parts of the NHS. The Conservatives have denied that, but "not for sale" has become a Labour rallying cry.
Aside from Brexit and the NHS, politicians on all sides are talking about the environment.
A poll commissioned by ClientEarth, a campaign group that seeks legal means to achieve environmental improvements, found that 70% of people want more urgent action on climate change and 54% will decide how they vote at least in part based on the parties' stance on the issue.
Of the 2,000 people questioned, 61% said they wanted the UK to bring forward its target for becoming carbon-neutral from 2050.
Possibly as a result of voter concerns, the Conservative government reversed its policy supporting fracking and imposed a moratorium on the gas extraction technique, citing safety concerns.
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And the most online?
"The amount of money spent on digital advertising is increasing with every election. But electoral law was written long before campaigning went digital."
So says the the UK's Electoral Commission.
Rules written in the analogue era and covering things such as advertising and campaign spending rules are inadequate for the digital age, it says, and has called for all online political adverts to state clearly who has paid for them, for social media companies to have online databases of political adverts, and for stronger regulatory powers to punish parties that break the rules.
Those changes have yet to happen and the parties' online strategies are bound to come under intense scrutiny.
With similar concerns in the US and elsewhere, Twitter has banned political adverts, but Facebook has not.