Far-right and anti-European Union parties made sweeping gains in European Parliament elections Sunday — triggering what one prime minister called a political "earthquake" by those who want to slash the powers of the EU or abolish it altogether.

Voters in 21 of the EU's 28 nations went to the polls Sunday, choosing lawmakers for the bloc's 751-seat legislature. The other seven countries in the bloc had already voted in a process that began Thursday in Britain and the Netherlands.

One of the most significant winners was France's far-right, anti-immigrant National Front party, which was the outright winner in France — with 26 percent support, or 4.1 million votes. The National Front, like other far-right parties across Europe, promotes anti-immigrant and often anti-Semitic policies.

"The sovereign people have spoken ... acclaiming they want to take back the reins of their destiny," party leader Marine Le Pen said in a statement. She called the results "the first step in a long march to liberty."

She also called for the French National Assembly to be dissolved on the basis of the results.

"What else can the president do after such a rejection?” she said. "It is unacceptable that the assembly should be so unrepresentative of the French people."

French Prime Minister Manuel Valls, in a televised speech, called the National Front win "more than a news alert ... It is a shock, an earthquake."

French President François Hollande's office announced he would hold urgent talks first thing Monday with top government ministers in what French media called a crisis meeting.

Estimated voter turnout, 43.1 percent, was narrowly up from the last European Parliament election's in 2009, reversing years of decline, and now, all of Europe will have to deal with the fallout of the elections, analysts and politicians said.

Pro-European parties "have to take very seriously what is behind the vote," of the so-called Euroskeptics, said Martin Schulz of the Socialist group in the European Parliament.

To the Euroskeptics, Brussels epitomizes bureaucratic inefficiency and infringes on national sovereignty at a time when the financial crisis has left 23.5 percent of European youth unemployed. Richer northern nations have ended up footing the bill while being unable to manage their currencies or key policies themselves, Euroskeptics say.

That said, Guy Verhofstadt, leader of the liberal caucus in the European Parliament, pointed out that even after the vote, two-thirds of the European lawmakers would be "people who are in favor of the European Union."

Despite the anti-EU gains, established pro-EU parties were forecast to remain the biggest groups in the parliament. The conservative caucus, known as EPP, was forecast to win 211 seats, down from 274 but enough to remain the body's biggest group.

Doru Frantescu, policy director of independent Brussels-based VoteWatch Europe, said Europe's mainstream political parties still won enough seats to muster a majority on issues where they concur.

"The problem comes when the left, the Socialists and EPP will not agree on issues," Frantescu said.

In the incoming European Parliament, he said, fringe parties will be able to exert more pressure on key topics, ranging from how liberal to make the internal European market for services to the proper mix of energy sources to which clauses should be scrapped in a proposed trade and investment agreement with the United States.