Marine Le Pen's far-right party has edged just ahead of President Emmanuel Macron's centrist alliance in French exit polls for the European elections.
The National Rally scored a first-place finish in a narrow victory of just one seat, according to the first official projection of the night on Sunday.
Pollsters have expected a nationalist surge in the EU parliament election and the projected vote share dealt a blow for French President Mr Macron.
The first official projection of all 751 seats by the European Parliament indicated that losses for the pro-EU centre may have been no worse than expected, with the Greens and liberals also gaining at the expense of the centre-right and centre-left.
Brussels officials and pro-EU party leaders also took heart from a substantial increase in turnout - the first in the 40-year history of direct elections to the Parliament.
It was about 50 per cent, up from 43 per cent in 2014 - hardly massive, but an end to the declines that have fueled talk of a "democratic deficit" that undermines the legitimacy of EU lawmaking.
Dropping about 40 seats each, the conservative European People's Party and Socialists & Democrats lost the majority they formed in a "grand coalition" with the EPP on top, according to the projection.
Gains for the liberal ALDE and its allies under Mr Macron put them in the frame for a bigger say. The Greens, in fourth place, could be kingmakers as the Socialists eye their chances of taking a lead, despite again trailing the EPP by 20-30 seats.
Agencies contributed to this report
