(CNN) -- France's far-right National Front party was projected to win a nationwide election for the first time on Sunday following a European parliamentary vote, French media reported, citing exit poll results.
Garnering an estimated 25% of votes, the National Front came in ahead of the center-right UMP, which scored 20.3%, and President Francois Hollande's Socialist Party, which came in third with 14.7%, according to French media.
Participation in the vote was around 46% as of 8:30 p.m. (2:30 p.m. ET), France's Interior Ministry said.
"This election is more than a warning. It is a shock, an earthquake," Socialist Prime Minister Manuel Valls said, according to a summary of his remarks posted on the French government's website. "None of us can shirk their responsibilities."
He described the election as "a very serious moment for France and for Europe," noting that projections indicate that voters are skeptical of the European Union.
Voters across Europe have been casting ballots for days in the parliamentary vote. There are 751 seats from 28 countries up for grabs. France has 74 seats.
Nearly 400 million Europeans were eligible to vote. Turnout was about 43%, Parliament spokesman Jaume Duch said, according to a summary of election results and reactions posted on the European Parliament's official elections website.
Before the election, analysts predicted that protest parties were likely to triumph at the polls.
Those parties are demanding tighter border controls, nationalized decision-making and a dissolution of the currency union.
But the parties have little in common aside from a dislike of the Brussels bureaucracy, and a pan-euroskeptic political group is unlikely, political scientist Duncan McDonnell told CNN last week.
"The euroskeptic label covers parties of both right and left, many of whom object to the EU for very different reasons -- the radical left denounce Europe as a free-market-promoting friend of high finance, while the right objects to a loss of national sovereignty and bureaucracy," said McDonnell, a political science fellow at the European University Institute in Florence.
CNN's Jim Boulden and Ivana Kottasova contributed to this report.
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