Voting is already under way as 28 European states vote over four days in EU elections.
To avoid accidentally influencing the vote elsewhere, any results and exit polls are top secret until Sunday night. There can be no reporting of projected results.
But on Sunday, everything will emerge over the course of a few hours.
Here are some key things to watch out for.
Keep an eye on Europe’s traditional powerhouse
The centre-right and centre-left parties have been the dominant power in every European Parliament. Between them, the European People’s Party (EPP) and Socialists and Democrats (S&D) have always had more than 50% of the seats between them.
No-one is predicting a drastic change in the old order – but more of a gradual chipping away at the establishment.
The key will be whether the two parties drop from a combined strength of just over half of MEPs to just under half.
That small change would be historic – and might reflect the rising importance of the smaller parties. No longer would the two biggest players be able to form a majority by themselves.
Watch for new alliance of the far right
Europe’s right-wing nationalists have rarely succeeded in finding common ground – but this time they have tried very hard to do so.
Italy’s Matteo Salvini is trying to create a powerful bloc in the Parliament, which he is calling the European Alliance for People and Nations.
On 18 May he gathered 12 far-right parties for a campaign rally, from Bulgaria in the east to Finland in the north, taking in France’s high-profile National Rally and Germany’s AfD.
Such a group, if it emerges, could be a major force.
Will more women get elected?
Every European Parliament election has seen the representation of women as MEPs rise, slowly but steadily – from 15% in 1974 to 37% in 2014.
The uncertainty around the shift in the vote this time means there is no guarantee that trend will continue – and any decline, no matter how small, would be a first.
Women in the European Parliament
As a percentage of total MEPs, 1984-2019
There is also the issue of who will take the top jobs in the European Commission – the executive body of the EU.
Most of the top jobs are held by men.
In the existing setup, there is just one woman – foreign policy chief Federica Mogherini – in office.
Two women are among the six candidates currently vying for the top job in the European Commission. A decision will not be made on the Commission jobs until later.
How will Austria’s scandal play out?
Austria’s coalition of the far right and conservatives served as a model for nationalists – until it came crashing down in the days leading up to these elections.
Little over a week before Austrians went to vote, a video from 2017 emerged on German media showing the leader of the far-right Freedom Party apparently promising government contracts in exchange for election support.
All the Freedom Party ministers resigned or were fired and conservative Chancellor Sebastian Kurz is left facing a no-confidence vote the day after Sunday’s election result.
No-one knows how the two parties will fare.
Can Macron be a new face for Europe?
France’s President Emmanuel Macron has often campaigned on pro-European issues, attempting to place France at the heart of Europe and tackle rising Euroscepticism.
This is the first time his LREM party has fought a European election, and running under the name Renaissance it faces a strong challenge from the far-right National Rally, fronted by Marine Le Pen.
Even a narrow defeat would be a blow at home, where he has been dealing with months of protests from the Yellow Vest movement.
Then there’s the question of where this new player would fit in the European Parliament.
The obvious choice would be the Alliance of Liberals and Democrats for Europe (ALDE) – but the two have their differences and Mr Macron’s party is eyeing other parties outside the group too.
Will there be a green wave?
Some of the smaller groups in the European Parliament are looking to attract votes from the left, and the European Greens are hoping to capitalise on the spread of climate change protests.
In the run-up to the elections, there was much talk of a “green wave” for the environmentalist parties. It has been strongest in Germany, where the party is hoping for substantial gains.
Climate change is seen as one of the top two issues for voters in Denmark, Sweden and Finland, but that may not translate into Green votes.
What will Hungary’s Orban do next?
Prime Minister Viktor Orban and his nationalist Fidesz party are popular in Hungary but not flavour of the month in the EU.
Fidesz has been suspended from the centre-right EPP, the largest European Parliament group, over its anti-EU rhetoric and targeting of senior EPP members in campaign ads.
So the choice he has is whether to fight to stay in the centre right or join the emerging alliance of nationalist, anti-immigration parties.
That would provide Matteo Salvini’s group with a sizeable bonus, but even though the two leaders see eye to eye on many issues, Mr Orban has not said what will do next.