AMSTERDAM • Today, 12.9 million eligible Dutch voters cast their ballots in an election that was seen as a test of anti-immigrant sentiment even before a rift with Turkey put immigration and nationalism at the top of the political agenda.

With many voters appearing to be undecided which of the record 28 parties in the running to choose, politicians hit the airwaves and the campaign trail yesterday to try to sway them.

Outgoing Prime Minister Mark Rutte and his People's Party for Freedom and Democracy are topping the latest polls, and poised to win by a whisker with a predicted 24 to 28 seats in the 150-seat Parliament. But he is fighting off a stiff challenge from the Party for Freedom of his rival, far-right anti-Islam MP Geert Wilders, which may scoop up 20 to 24 seats. In a one-page manifesto, Mr Wilders has pledged to close the borders to Muslim immigrants, shut mosques and ban sales of the Quran.

The two men clashed on Monday in their only televised head-to-head debate, laying out sharply different visions for the future.

Mr Rutte again stressed that he would never work with his rival, a stand that could complicate moves to form a coalition government. Bidding for a third term, he pointed to his six years as premier overseeing growth, in one of the euro zone's leading economies, and the need for stability for the country's 17 million people.

But a diplomatic row with Turkey, which has suspended its 400-year-old ties with the Netherlands and triggered incendiary accusations from Turkish President Recep Tayyip Erdogan, has gate-crashed the polls.

"You are being taken hostage by Erdogan. Close the Dutch borders," Mr Wilders told Mr Rutte, as tempers flared late on Monday.

"That is a totally fake solution," Mr Rutte shot back, "you want Nexit, you want the Netherlands out of Europe. You know what it will cost... don't do it."

While Mr Wilders's views have won growing support amid Europe's refugee crisis, many of the pragmatic Dutch still find them unpalatable.

In the wake of last year's Brexit vote and the election of Mr Donald Trump as US President, the Dutch elections are being keenly watched to measure the strength of far-right and populist parties ahead of other elections in Europe. The French presidential election begins next month, with the far-right Marine Le Pen ahead in one poll on Monday. In September, Alternative for Germany, a right-wing, euro-sceptic party, is likely to win seats for the first time in the German federal Parliament.

Amid such a fragmented political landscape and the possibility that the next government would comprise an unwieldy four- or five-party coalition, a lot of Dutch may well vote strategically.

AGENCE FRANCE-PRESSE, REUTERS