London (CNN) Prime Minister Theresa May looks like she's lost her government majority in the UK election, according to the official exit poll. A hung parliament -- where there is no overall winner -- would make a huge difference to Brexit. Here's what might happen, depending on the final results:
Conservatives short of a majority -- hung parliament:
A disaster for the PM, because she has thrown away the first Conservative majority government for 18 years after just two.
Even if the Tories are the largest party with the most number of seats and will therefore have the first chance to form a government, she will find it difficult to go into coalition with a smaller party like the Liberal Democrats, who are fundamentally opposed to Brexit.
There is no chance of her doing a deal with Labour or the Scottish National Party, who are on opposite sides of the political divide to the Conservatives. She might be able to form a coalition with the Northern Ireland party the DUP, who are in favor of Brexit, but they are themselves set to lose seats on June 8 and the numbers might not be enough for an overall majority. In any case, some Conservative MPs will be so furious that power has been lost after an unnecessary election and will demand she steps down.
Conservative majority of between one and 11 seats:
A technical win for the Prime Minister's party but a major personal setback, because at least one Conservative MP will have lost a seat in an election campaign that did not need to happen for three years.
Her personal authority over the party and her ability to get tough in Brexit talks will be severely undermined, and there will be pressure on her to resign. She could stay on to ensure some stability for Brexit negotiations but some Tory MPs will start moving against her once they are underway.
Conservative majority of between 12 and 50 seats
This is a danger zone for the Prime Minister, because 12 is her majority right now -- meaning she would have put her party and the country through a long, difficult election for very little or no reward.
Eurosceptic Conservative MPs would hold her to her word on a "hard Brexit", meaning if she came away from negotiations in Brussels with anything less than her red lines, they would start putting pressure on her as leader. Essentially, the smaller May's majority gets, the harder Brexit is likely to be.
Labour largest party in a hung parliament:
Even though some believe that the polls, having got the 2015 election and 2016 Brexit results wrong, are overstating Labour's figure by predicting a hung parliament, those polls still point to the Conservatives having the most seats.
In the unlikely event that Jeremy Corbyn's party emerges with the most seats, he will get the first chance to try to form a government. He could form a left-wing "progressive alliance" with the SNP and Liberal Democrats. Labour has pledged to go ahead with Brexit but with a much softer version -- including keeping some aspects of single market membership.
Therefore a left-wing coalition would lead to Prime Minister Corbyn going into Brexit talks with a plan for soft Brexit. From the Brussels side, negotiators are unlikely to allow Britain to stay in the single market without major concessions on immigration and freedom of movement, one of the conditions of membership.
The Lib Dems are more fiercely opposed to Brexit and want whatever deal is reached to be put to a second referendum, which could be one of their red lines in coalition talks.
Labour outright majority:
None of the polls have predicted this outcome, so it is seen as highly unlikely. But, in this scenario, Labour's plan is to go ahead with Brexit but to push for Britain to remain part of the single market.
As above, this deal is unlikely to be struck in Brussels without Labour accepting freedom of movement. Labour have also pledged to hold a vote in Parliament on the final deal.