Dutch anti-immigration populists stunned Prime Minister Mark Rutte to become the largest party in the senate Thursday following elections that took place just days after a suspected terror attack.

Thierry Baudet's Forum for Democracy party, which also backs a "Nexit" from the EU, came from nowhere to win most votes in Wednesday's provincial elections, with more than 98 percent of ballots counted, the NOS broadcaster said.

The result will ring alarm bells across Europe where populists are expected to make big gains in European Parliament elections in May.

Baudet, 36, a former academic with a history of controversial comments about women and immigration who backs closer relations with Russia, accused Rutte of "arrogance and stupidity".

"We stand here in the rubble of what was once the most beautiful civilisation," he told a cheering crowd late Wednesday in a speech laced with classical references.


The party, which only launched two years ago, will now be the largest in the upper house of parliament with 13 seats, followed by Rutte's party with 12 seats, the Dutch news agency ANP said.

The final shape of the 75-seat senate will be determined in May by the 570 representatives elected to the country's 12 provinces in Wednesday's election.

Turnout was 56%, up from 48% in 2015.

Dutch newspapers reacted with astonishment to the results. Algemeen Dagblad said "Baudet grabs mega-win" while De Telegraaf said simply: "Landslide".

Rutte, an influential figure in Europe's negotiations with London over Britain's departure from the EU, will now have to rely on other parties to get laws through the senate.

The coalition led by Rutte's centre-right VVD party - set up after a 2017 general election to keep far-right leader Geert Wilders out of power after he too won a surge in votes - is set to collapse from 38 to 31 seats.

"We are going to have to get to work," Rutte told supporters. "We have to talk with other parties so we can continue to lead this country well."

'Borders wide open'

Rutte said he may have to work with leftist parties including the ecological party GroenLinks (Green Left) party led by Jesse Klaver, which had a good night and is set to double its seats from four to eight.

But Rutte said he was not discarding the possibility of working with Baudet, saying he was looking forward to contacting him "to see how we can get to sensible majorities."

"What I hope is that the Forum for Democracy, now that it has become so large, is ready to consolidate the basis of political management in the Netherlands," he told reporters on Thursday before heading to Brussels for an EU summit.

Baudet has previously called for the Netherlands to immediately leave the EU but has recently softened his rhetoric due to the chaos over Brexit.

However he kept up his fiery tone on multiculturalism and immigration, and made references in his speech to the shooting on a tram in the city of Utrecht on Monday in which three people died.

A Turkish-born man is to be charged with "terrorist" murder or manslaughter over the attack.

The populist faced criticism after failing to stop campaigning on the day of the shooting.

"We are being destroyed by the people who are supposed to be protecting us," he said Wednesday night.

"Successive Rutte governments have left our borders wide open, letting in hundreds of thousands of people with cultures completely different to ours."

Baudet is also known for controversial statements such as "women in general excel less in jobs and have less ambition".

Baudet seemed to have taken votes from Wilders, whose anti-Islam Freedom Party is set to win five seats, down from nine, amid signs that his fierce rhetoric is alienating voters.

The Netherlands has had a long line of flamboyant populist leaders dating back to Pim Fortuyn, the gay anti-immigration politician who was assassinated in 2002 by an animal activist.