By Anna Holligan & Paul Kirby In The Hague and LondonBBC News
Sem van der Wal/EPA-EFE/REX/ShutterstockA stunned Caroline van der Plas said that Dutch voters had spokenA farmers' party has stunned Dutch politics, and is set to be the biggest party in the upper house of parliament after provincial elections.
The Farmer-citizen movement (BBB) was only set up in 2019 in the wake of widespread farmers' protests.
But with most votes counted they are due to win 15 of the Senate's seats with almost 20% of the vote.
"This isn't normal, but actually it is! It's all normal citizens who voted," said leader Caroline van der Plas.
The BBB aims to fight government plans to slash nitrogen emissions harmful to biodiversity by dramatically reducing livestock numbers and buying out thousands of farms.
But its appeal has spread rapidly beyond its rural heartland, on a populist platform that represents traditional, conservative Dutch social and moral values.
Shocked by the scale of their success, Ms van der Plas told supporters that voters normally stayed at home if they lost faith in politics: "But today people have shown they can't stay at home any longer. We won't be ignored any more."
A left-wing Green-Labour alliance is also on course to win 15 Senate seats, while Prime Minister Mark Rutte's four-party coalition is poised to fall back to 24 - down eight seats.
Turnout in Wednesday's vote, estimated at 57.5%, was the highest for years and the biggest loser of the night was the far-right Forum for Democracy party.
For rural voters, the main incentive for backing the BBB was to protest against cuts in nitrogen emissions, according to an Ipsos poll for public broadcaster NOS.
But voters also turned out in force for the Greens, and environmental groups warned that the Netherlands' problems were not going away.
"Restoring nature is just as necessary today and tomorrow as it was yesterday," tweeted Natuurmonumenten.
The run-up to the vote was dominated by the sight of farmers' tractors on the streets of The Hague and outside the venue that hosted a pre-vote leaders' debate.
JEROEN JUMELET/EPA-EFE/REX/ShutterstockTractors took part in a noisy protest on the eve of the vote in the southern city of Den BoschCommentator Ben Coates described the result as "something of an earthquake in Dutch politics".
Although their policies are very much focused on opposing the government's environmental policies, he told the BBC most people would characterise them as a right-wing, populist party that was quite anti-EU, anti-immigration and in favour of banning burkas for Muslims.
Standing before supporters on Wednesday night, Caroline van der Plas wore her trademark green nail polish and a ring featuring an upside-down Dutch flag, a symbol of the anti-government protests.
The daughter of an Irish mother and a Dutch father, she lost her husband Jan to pancreatic cancer as the protests took off in 2019. She is unlike any Dutch party leader - and for many voters, that is her appeal.
She had to step back from public campaigning last year because of death threats. She was told the same fate awaited her as Pim Fortuyn, a populist leader assassinated days before the 2002 Dutch general election.
Speaking to the BBC during a visit to farmers in the rural east, she sprang to her feet in mid-sentence to avoid a bee, explaining she had been stung as a toddler and had been terrified ever since.
Dutch farmers clogged up more than 1,000km during 2019's protestsBBC in other languagesInnovationncG1vNJzZmivp6x7o67CZ5qopV%2Bjsri%2FjrCmq6SUYrK2vs6pnGZuZG6DeIGQbA%3D%3D