Polling stations have opened their doors in 21 member countries, including the major EU states of Germany, France, Italy, Spain and Poland. These five together send almost half of all MEPs to the European Parliament: 348 out of a total 751.
Voting in the world's only international parliament began on Thursday with the Netherlands and the UK, followed by Ireland and the Czech Republic on Friday and Latvia, Malta and Slovakia on Saturday. A total of 420 million citizens are eligible to cast their ballot. Election researchers expect the low turnout of the previous vote in 2014, which was only 43%, could rise slightly this time around.
Read more: Forward or backward? Decision time in the EU
Liberal democracy vs. nationalism
The EU's largest parties have said this year's vote could be a life-changing election.
The leading candidate for the center-right European People's Party (EPP), Germany's Manfred Weber, and the frontman of the center-left Party of European Socialists (PES), Frans Timmermans, the outgoing European Commission vice president from the Netherlands, both agreed on this point during the election campaign.
Their top concern in this election is to maintain cohesion in the EU, defending the "liberal" democracies against the "illiberal" model backed by nationalists and populists, among them Hungarian Prime Minister Viktor Orban.
French President Emmanuel Macron has made calls for a "Europe that protects," and wants far-reaching reforms in the social and economic fields. Italian right-wing populist leader Matteo Salvini, on the other hand, wants to radically reduce cooperation in Europe.
Like right-wing populists in numerous EU member states, Salvini follows the motto of "My country first!" His party will probably be the most influential force in Italy in this election.
Collapse in Austria
The final week before the election was certainly not lacking in drama. In Austria, the conservative coalition government collapsed after a member of the far-right Freedom Party, then leader Heinz-Christian Strache, was caught out on video appearing to offer public contracts to a supposed niece of a Russian oligarch in return for campaign help.
Election researchers remain skeptical as to whether this scandal will have an impact on the wider EU vote. Davide Ferrari, of the VoteWatch research institute in Brussels, told DW that the effect would likely be limited to Austria. "Right-wing voters aren't so concerned about ethics. For them, it's about the protest," he said.
According to polls taken across the 28 member states, right-wing populists and EU opponents could take 20 to 23% of the seats in the newly elected parliament. A significant increase, says Janis Emmanouilidis of the European Policy Centre think tank, but "not enough to take power." He believes it will be difficult for the right to form a unified group in the new parliament.
Madness in the UK
Of all the representatives to be elected, it could be those from the United Kingdom who change the structure of the new parliament. With a Brexit process still outstanding, British citizens were still eligible to take part in Thursday's vote. The newly established Brexit Party will likely come out on top, but EU supporters and liberals could also do well.
The outcome is expected to be disastrous for the ruling Conservatives, with ineffective Prime Minister Theresa May conceding defeat on Brexit and announcing her resignation on Friday. However, the official results from the UK — just like those from the other EU states — will only be published late Sunday evening.
The British Labour Party, though also bogged down in the Brexit swamp, will probably send around 20 MEPs to Strasbourg. This is good news for their European colleagues, who had feared a downsizing initially predicted in early polling. The surprisingly good result for PES leader Timmermans in the Netherlands on Thursday also gave the group a little boost, even if it's just two extra seats. However, the British MEPs may disappear in October, if Brexit is actually implemented, meaning the group would shrink.
Implications for Berlin
The performance of Weber, the EPP's leading candidate, who also represents the conservative Christian Social Union in Germany, will have an impact on domestic policy in Berlin.
Ursula Münch, the director of the Academy for Political Education in Tutzing, near Munich, told DW that she expected losses for the three parties that make up the governing coalition, Chancellor Angela Merkel's Christian Democratic Union, its sister party, the Christian Social Union, and the Social Democrats. Münch believes the results of the EU elections could bring about a premature end to the coalition, or even see the replacement of Merkel as chancellor.
In recent weeks, some member states have shifted the focus of their election campaigns. In Germany and Denmark, the fight against climate change has been a key campaign issue. In Greece and Italy, voters are arguing about economic policy and the EU's perceived paternalism.
Hungary's Viktor Orban, who wants to save Christianity in Europe from a "flood of Islamic migrants," has kept the topic of migration high on his agenda. However, most voters outside Hungary don't really consider that to be a threat.
'Moment of European democracy'
A question of fate, a crossroads, a fork in the road, the last chance? While the election is certainly important, European Commission spokesman Margaritis Schinas has said one need not exaggerate.
"I've been in European politics for several years. I can't remember any vote where it wasn't about 'Europe being at a crossroad.' This is what we will always face, and that's a good thing," Schinas said recently in an interview with broadcaster Euronews. "This is the moment of European democracy, and we should also enjoy it."
The first projected outcome of the new European Parliament is expected shortly after 8 p.m. in Brussels.