AMSTERDAM — The parochial world of Dutch elections is not often seen as a hotbed of foreign intrigue. But in recent months, an unexpected worry has emerged: the influence of American money.
The country’s fast-rising far-right leader, Geert Wilders, is getting help from American conservatives attracted to his anti-European Union and anti-Islam views. David Horowitz, an American right-wing activist, has contributed roughly $150,000 to Mr. Wilders’s Party for Freedom over two years — of which nearly $120,000 came in 2015, making it the largest individual contribution in the Dutch political system that year, according to recently released records.
By American standards, the amount is a pittance. But to some Dutch, who are already fearful of possible Russian meddling in the election, the American involvement is an assault on national sovereignty.
“It’s foreign interference in our democracy,” said Ronald van Raak, a senior member of Parliament in the opposition Socialist party, who has co-sponsored legislation to ban foreign donations. “We would not have thought that people from other countries would have been interested in our politics,” he said. “Maybe we underestimated ourselves.”
The Dutch parliamentary elections on March 15 are the kickoff for a pivotal political year in Europe. Other elections loom in France, Germany and possibly Italy. With the viability of the European Union at stake, anxieties are rising about foreign interference, with European intelligence agencies warning that Russia is working to help far-right parties through hacking and disinformation campaigns.
But sympathy for Europe’s far right is also coming from Americans who share similar views and are willing to contribute money to help the cause. Measuring this outside support is difficult, though, because many European countries have leaky, opaque accountability systems on campaign finance.
France, Germany and the Netherlands have only published campaign finance data from as recently as 2014 or 2015. And only the Netherlands will update that information with more disclosures before Election Day. New campaign finance data is expected to be released on Wednesday.
Though Europe is generally known for its public financing of elections, parties are increasingly seeking outside donations, especially since regulatory loopholes abound. In Germany, the far-right Alternative for Germany sold gold bars and coins in a strategy to inflate its revenue and, through a quirk of the rules, increase its access to public funds, until the practice was banned by Parliament. German parties have also sought to divert public funds provided to parliamentary caucuses.
“It’s illegal but basically done everywhere” in Germany, said Christoph Möllers, a professor of public law and legal philosophy at Humboldt University of Berlin.
While France bars contributions from businesses, loans are allowed. A Russian bank made headlines in recent years after lending millions of euros to the far-right National Front party of Marine Le Pen. After that bank failed last year, the party complained that it had been shunned by French banks and declared itself in the market for a new lender.
If nothing else, European far-right parties are gaining newly emboldened allies.
“I expect the Trump administration to be more open to these parties than Obama, certainly,” said Representative Steve King, an Iowa Republican who is an ally both of President Trump and the European far right, having met with various party leaders during a recent European trip.
The State Department, in a statement, declined “to comment on political parties in foreign elections.”
Mr. Horowitz, who has long sounded alarms on Muslim immigration, first rallied to Mr. Wilders’s side after the Dutch politician was put on trial in 2010 for inciting hatred against Muslims with a film he made that attacked the Quran; he was acquitted the next year. Mr. Wilders was more recently found guilty of incitement after leading an anti-Moroccan chant at a rally, though he avoided a fine.
“I think he’s the Paul Revere of Europe,” Mr. Horowitz said in an interview. “Geert Wilders is a hero, and I think he’s a hero of the most important battle of our times, the battle to defend free speech,” he added, calling the situation in Europe a “nightmare.”
Though Mr. Horowitz’s donations adhere to Dutch standards, there was some question of whether they comply with American law.
Organized as a 501(c)(3) under American tax law, Mr. Horowitz’s foundation is barred from making donations to political organizations. The donations went to the Friends of PVV, according to Dutch records, a foundation covered by political disclosure rules.
Michael Finch, the president of Mr. Horowitz’s foundation, said in an email that “the funds that were sent to Geert Wilders were to help him in his legal cases” and “were not political donations.”
But donations to foreign political entities are problematic, tax experts said.
“The I.R.S. views foreign political organizations as the same as domestic political organizations — not appropriate for a charity to support,” said Marcus S. Owens, a partner at Loeb & Loeb, and former director of the Exempt Organizations Division of the Internal Revenue Service, in an email. He added, “The I.R.S. also views a charity that is controlled by a political organization as transgressing federal tax rules.”
Mr. Horowitz said he was not certain if the foundation had given additional funds to Mr. Wilders’s party this year or last year.
Mr. Wilders’s backing of Israel, where he once lived, has set him apart from other far-right groups, and he has courted American Jews. Daniel Pipes, another conservative American activist and a Harvard-educated historian known for his controversial statements on Islam, said in an email exchange that he hoped “the rise of the insurgent parties leads not to their forming governments but their sending a strong message to the legacy parties to wake up and deal with the imperative issues they have so long ignored.”
Mr. Pipes said his foundation, the Middle East Forum, provided money in the “six figures” to help pay legal bills in Mr. Wilders’s trial over the film, but specifically to a legal fund, and has not provided political support. Mr. Pipes has called Mr. Wilders “the most important European alive today,” but has differed with him on his view of Islam, though he himself has expressed inflammatory views on the subject.
Dutch records also show that two American foundations paid for Mr. Wilders’s flights and hotels on trips to the United States last year. One, the Gatestone Institute, lists John R. Bolton, a combative former United Nations ambassador under George W. Bush, as its chairman. Another, the International Freedom Alliance Foundation, is backed by Robert J. Shillman, a wealthy Trump supporter who paid for a digital ad in Times Square last year depicting Mr. Trump as Superman. The travel payments were previously reported by Foreign Policy magazine.
Lawmakers and academics say the European public has seen little need for tight campaign finance regulations because political campaigning in Europe has historically been far more restrained than in the United States.
“The campaigns don’t seem to be that relevant,” Mr. Mollers said. “You see campaign finance is spent for posters, and no one believes that changes the game.”
Now, however, European political campaigns could become more expensive as parties turn to data-driven persuasion efforts similar to those used in the United States, even if they are limited by European data-protection laws. The Dutch Green Party, for instance, has licensed software from Blue State Digital, a prominent American data consultancy.
Guillaume Liegey, co-founder and chief executive of Liegey Muller Pons, a data consulting firm, was an adviser to President François Hollande’s 2012 campaign in France, one of the first in Europe to use data-driven techniques.
“The idea of using data and technology has since then become more of a standard in today’s European campaigns,” he said in an email. He now consults for the campaign of Emmanuel Macron, a left-leaning politician who is one of the front-runners in the French presidential race, which takes place in two stages in April and May.
Few dispute the stakes. Mr. Wilders and Ms. Le Pen, the French far-right leader, are running strong in polls, though both are considered long shots to win control of their governments. If either did win, it could be a devastating blow to the euro currency union, as well as the European Union itself, an outcome that many analysts regard as a foreign policy disaster.
Mr. Horowitz disagrees, and portrays the European Union as the disaster.
“To have this Parliament that represents nobody in Brussels making laws for everybody, it’s very anti-democratic,” said Mr. Horowitz. “I always thought it was a bad idea.”
An earlier version of this article misstated the group to which David Horowitz was referring in a speech. He used the phrase “sick death cult” in reference to Hamas, not Islam.