Her decision to hold an election while Brexit negotiations have barely gotten started has taken everyone in Westminster and Brussels by surprise -- particularly as she has consistently said she would not go to the country before 2020.
It is a high-risk decision, and will bring further uncertainty to a Europe undergoing huge political turbulence, with elections in France and Germany to come later this year.
Yet, from her point of view, she had little choice. Her party's working majority in Parliament is only 17, giving her a weak hand over her political rivals in Britain just as she needs unity in negotiating her country's exit from the European Union.
If she were to win with an increased majority, it would settle once and for all the debate about whether the British people voted for the "hard Brexit" that May is attempting to negotiate, with its clean break from Europe's single market and her threat to walk away with no deal if she does not get what she wants.
There has been a growing sense that if May wanted to call an early election, it was now or never: fighting an election campaign whilst Brexit negotiations were in full swing would have been near impossible. A snap election also outmaneuvers the Scottish National Party, which is using Brexit to push for a second referendum on Scottish independence, arguing that Scotland voted to remain a member of the EU.
A victory in June for May's Conservative Party would give her the personal mandate for Brexit she needs and, as she said herself in her surprise statement in Downing Street, make her stronger when she fights for a deal with fellow European leaders.
May said she was reluctant to call for an election and has only recently come to the decision because of what she described as "political game-playing" by opposition parties in Westminster. She said Labour, the Liberal Democrats and the SNP were all trying to block Brexit, creating "division and disunity".
Yet this is a weak and spurious reason for calling an election: opposition parties, particularly those who officially supported remaining in the EU, are supposed to oppose the government -- that is their job. The Prime Minister has never come close to losing a vote in the Commons on Brexit, so her position was never under threat.
What's more astounding is May's claim that the country was "uniting" around Brexit. This is simply not true. The UK remains divided about whether it is right to leave the EU.
By seeking a mandate for Brexit through a general election, she is tacitly admitting she does not have a mandate for Brexit -- at least her hard, "no deal" version -- at the moment.
So in accusing others of political game-playing, the Prime Minister is game-playing herself. But what ultimately matters is that, with the Conservatives leading the main opposition party Labour in the polls by at least 20 points, May is likely to win a landslide on June 8
. This will give her the authority to fight for a better Brexit deal from the EU -- which is bad news for Brussels.
Next month, an anti-EU candidate may win the French presidency. It would be hard for Brussels to hold the EU project together in the face of strengthened nationalist governments in the UK and France. When European Council President Donald Tusk tweeted earlier
: "It was Hitchcock who directed Brexit: first an earthquake and the tension rises," perhaps he should have added that there are plenty more earthquakes to come.