European populism faced its first big electoral test since last year’s “Brexit” referendum and Donald J. Trump’s election. Turnout was the highest in decades. The main exit poll indicated that the largest party in Parliament will remain the center-right party of Mark Rutte, the prime minister, with 31 of 150 seats. He has moved rightward in recent months, making tougher pronouncements on immigration but steering clear of the xenophobic and borderline racist statements of other parties. The far-right populist party of Geert Wilders gained seats, but did not perform as strongly as expected. Exit polls suggested that it was tied for second place with the conservative party Christian Democratic Appeal and the center-left pro-European party Democrats 66 — each with 19 seats. Also making a relatively strong showing were the left-leaning Greens, with 16 seats. The leftist, euroskeptic Socialist Party is projected to have 14 seats.
The big loser appeared to be the mainstream Labor party, which had governed with the mainstream conservatives led by Mr. Rutte. The exit poll put it in seventh place, with nine seats.
Turnout was 82 percent, the highest in decades. All 150 seats in the lower (and more powerful) house of Parliament are up for grabs. It takes a simple majority, 76 seats, to govern. Coalitions are the norm. The landscape is highly fragmented, with 11 parties represented in the current Parliament and 13 parties expected to be in the next one.