As polls closed in Ireland on Friday, pro-EU parties looked likely to scoop a large number of seats up for grabs in the European Parliament.
A Friday exit poll put Irish Taoiseach Leo Varadkar's Fine Gael party in the lead on Friday after a campaign dominated by concerns about Brexit.
Pro-EU Fine Gael candidates were ahead in two of Ireland's three constituencies, with the Greens coming first in Dublin, the poll of around 3,000 voters conducted by TV channels RTE and TG4 in Dublin suggested.
As he cast his vote in Dublin earlier on Friday, Mr Varadkar warned that Brexit was entering a "very dangerous" phase following the resignation of Prime Minister Theresa May as a more hardline politician could replace her.
"But whatever happens, we're going to hold our nerve.
"We're going to continue to build and strengthen and deepen our alliances across the European Union and we'll make sure that we see Ireland through this," he said.
More than 400 million people are eligible to elect 751 MEPs continent-wide, with the first official results to be announced late Sunday once voting in all 28 member states has been completed.
The Green Party also saw a surge in support in Ireland, if the polls are to be believed, with a predicted share of nine per cent of the vote. In Dublin, the party may take up to 23 per cent of the votes.
The polling news in Ireland matched similar polls in The Netherlands, which put mainstream Dutch parties that support the EU took 70 per cent of the vote, 3 per cent more than they did five years ago
Elsewhere in Europe, populist, eurosceptic forces were hoping for a stronger showing.
Matteo Salvini of Italy's anti-immigrant League and Marine Le Pen of France's far-right National Rally (RN) want their Europe of Nations and Freedom (ENF) group to become the third largest in Brussels. The League has topped opinion polls in Italy.
Ms Le Pen wants to strike a blow to Emmanuel Macron's faltering French presidency by overtaking his centrist, pro-European party Republic on the Move (LREM).