Vote counting in the European parliament races will begin Sunday morning.
The two-day elections to the European Parliament, the fourth in a row, started in the Czech Republic on Tuesday afternoon.
"It is hard to overstate the importance of this week's European Parliament elections", said Mujtaba Rahman of the Eurasia Group.
Babis' ANO (YES) movement is predicted to win up to 25% of the vote, followed by the moderate euroskeptic Civic Democratic Party and the pro-European Pirate party. But the polls also suggest that the far-right People's Party Our Slovakia will win seats in the European legislature for the first time. Its members use Nazi salutes, blame the Roma minority for crime, consider North Atlantic Treaty Organisation a terror group and want the country to leave the western military alliance and the EU.
The election reflects a continental struggle between nationalists who want to wrest power back from the European Union and moderates who want to make the European Union stronger. Voters in the Netherlands and Britain on Thursday kicked off four days of voting across the 28-nation bloc.
Many predict nationalists and far-right groups will gain ground.
Many predict nationalists and far-right groups will gain ground, and would try to use a larger presence in the legislature to claw back power from the European Union for their national governments. Moderate parties, on the other hand, want to cement closer ties among countries in the European Union, which was created in the wake of World War II to prevent renewed conflict.
Around the continent, pro-European leaders are seizing on the surprise in the Netherlands to mobilize their supporters to resist a populist gain, with opinion polls indicating nationalist parties lead in France, Italy and Hungary, among others. The Czech Republic is voting over both Friday and Saturday.
Hundreds of EU citizens trying to cast their vote for the European Parliament elections in the United Kingdom on Friday have been turned away because of administrative mistakes, a campaign group said.
Britain voted on Thursday, a day before Prime Minister Theresa May announced her resignation following a months-long Brexit crisis, though the result will not be revealed until Sunday.
Bloc-wide elections for the European Parliament will conclude today. Also defending seats in the European parliament will be the Christian Democrats and the Communists, who each have three MEPs in the assembly.
In the Netherlands, where turnout rose 4 percentage points from five years ago to 37 per cent, Mr Rutte's People's Party for Freedom and Democracy (VVD), came in second at 14 per cent, according to the Ipsos exit poll, which has a margin of error of 2 per cent. According to Czech law, any citizen aged over 18 can vote, so there are some 8.4 million eligible voters in the country with a population of 10.5 million.