An insurgent farmers’ party rode a wave of anger with the government in the Netherlands to triumph in provincial elections, dealing a blow to prime minister Mark Rutte’s ruling four-party coalition.

The populist Farmer Citizen Movement (BBB), which gained support from voters in rural areas and smaller towns, won the most seats in Wednesday’s election, according to an exit poll released on Thursday.

The provincial lawmakers elect national senators for the upper house of parliament at the end of May.

The BBB, founded in 2019, put itself at the head of often violent protests by farmers that erupted last year over plans to cut nitrous oxide emissions in half. To comply with a ruling by the country’s highest court, the government had announced plans for steep cuts to farm output.

Farms near protected areas would have to shut while others would be encouraged to reduce livestock herds or to exit the business in return for government compensation.

Rutte’s coalition is likely to lose a quarter of its senate seats after its vote share slumped from 40 per cent to 31 per cent amid widespread anger over the plans, the exit poll by Ipsos for broadcaster NOS found. It will now have to rely on other parties to get laws approved in the senate.

Nitrogen emissions from livestock manure and fertilisers, as well as vehicle exhausts and industry, pollute land and waterways, encouraging the growth of invasive species that crowd out wildlife.

Wopke Hoekstra, leader of the Christian Democrats and foreign minister, said: “Politicians in The Hague, including us, have not sufficiently understood what is going on in our country. There is a huge gap, we should all take that into account.”

His party, traditionally strong in the countryside, is projected to lose five seats in the senate. Overall, the coalition should have 24 seats in the 75-strong upper house, down from 32.

Caroline van der Plas, the BBB’s media-savvy leader and its only MP, said people who did not normally vote had flocked to the party, with voter turnout at 62 per cent, the highest in a provincial election since 1987.

“The coalition should take this very seriously,” she told NOS. “If this happened to me, I would be gone.”

As one of 15 parties contesting Wednesday’s elections, the BBB is projected to win 15 senate seats.

Sarah de Lange, a professor of politics at the University of Amsterdam, said the BBB fed off discontent from “left behind” communities. “They did well in peripheral parts of the country that feel neglected by The Hague. These are left behind places where public services, hospitals, schools are in decline.”

De Lange said the broad voting blocks in the Netherlands remained the same but votes were redistributed. In the cities, the progressive left, led by an alliance of the Greens and Labour, did well, while elsewhere the populist right prospered.

She said the government could get legislation through the senate by relying on the left on some policies, such as nitrogen cuts, and the right on others, such as reducing immigration.

However, the BBB will control several provinces that have to implement the nitrogen policy.

De Lange said the victory for the novice party could pose problems. She highlighted the fate of the far-right Forum for Democracy (FvD), which won 12 senate seats in 2019, but is projected to win just two this time.

“For the BBB it depends how organised they are. Just about every candidate was elected and they are inexperienced. The FvD had infighting and people leaving.”

The results will not be formally declared until next week.