Ms May’s entire reason for calling the vote was to give her a strong majority with which her party could confidently negotiate with Brussels and pass necessary legislation.
But instead the Tories must now rely on outside support and this could embolden anti-Brexit parties needed to form a coalition or provide informal support.
As the result began to become clear, a senior EU source telling The Independent: “Everyone here is shocked.
“We weren’t planning for this at all. We were expecting Ms May to have a 30 or 40-seat majority.
“It’s not clear how a coalition in Britain could work. There are suggestions there may have to be another election – we are in uncharted territory.”
While Britain has already started the clock ticking on leaving the EU by triggering the two-year negotiation period with Brussels, European Commission officials have suggested they could delay the opening of talks beyond the planned June 19 start date – but it is unlikely a few more days would help the UK get its act together.
As the biggest party, the Conservatives have the right to try and stay on either through a coalition deal or without a majority in the Commons.
But if the Prime Minister does choose to try and govern with a minority, it would leave her in an almost impossibly difficult situation.
She would need the votes of other parties – such as the Democratic Unionist Party – which have roundly rejected her approach to Brexit, in order to get one of the most complex and divisive legislative programmes in history through two chambers of Parliament – without having a majority in either.
Even if she could reach the point where she successfully passes the myriad laws needed before Brexit, and then agrees a deal with an EU, any final settlement would have to be put to a vote in a House of Commons with no united position.
Almost every other party believes Ms May’s Brexit plan would result in a hard rupture with Europe that would damage the economy, making a coalition very difficult.
Jeremy Corbyn has called for Ms May to resign, while some Conservatives have suggested she should "consider her position". The idea of a grand Brexit coalition between the Tories and Labour with the current Prime Minister at the helm is highly unlikely.
Even with another Tory leader, the compromises they would have to make to win Labour support for Brexit may make any deal untenable to the Conservative right.
A panicked Ukip leader Paul Nuttall said Brexit is in “jeopardy”, while ex-Bank of England Monetary Policy Committee member Danny Blanchflower took to Twitter to say: “If the exit polls are right Brexit is done best news ever.”
A potential coalition involving Labour, the SNP or the Liberal Democrats – looking past the fact that some parties have ruled out deals and pacts – could mean any Brexit deal would have to be put to a second referendum.
Figures in both the EU and in London have indicated that Article 50 – the triggering of which began the Brexit process – is reversible.
But turning it round now would take a huge amount of political will in both the UK and Brussels.
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