Flanders, the far right and Facebook.

That was the cocktail that helped the Belgian party Vlaams Belang (Flemish Interest) stage a surprise sorpasso in last weekend’s “triple election” to the federal, regional and European parliaments. As the results came in, the young guard currently in charge of the far-right, anti-immigrant, anti-Islam party saw that their strategy — conceived almost five years ago — had paid off.

Vlaams Belang won up to 18.5 percent of votes in Dutch-speaking Flanders, a whopping 12.6-point surge compared to the last triple elections in 2014. Isolated for the past three decades from the political mainstream by an anti-extremist cordon sanitaire, Vlaams Belang managed to come second behind Belgium’s largest party, the right-wing New Flemish Alliance (N-VA), which scored 24.8 percent.

Party Chairman Tom Van Grieken's description of the winning formula sounds deceptively simple: “We talked about people, our people, and they have to come first,” he told POLITICO on Monday, as Belgium's political establishment wondered how to respond to one of the biggest surprises of the weekend's voting. Dazed and confused, the country's more moderate political forces initially had few clues to offer on how they intend to break the resulting political deadlock and form federal and regional governments.

Facebook’s ads library reveals a social media strategy that was focused on the final weeks of the election campaign, and mostly targeted young voters aged 18 to 34.

Somehow, Vlaams Belang's campaign delivered it 15 parliamentary seats in the federal parliament, up from a previous three seats. In the Flemish region, the party jumps to 23 seats from six. Aligned at the EU level with Marine Le Pen’s far-right National Rally list in France and Matteo Salvini’s League party in Italy, the party will be sending three MEPs to the European Parliament as well.

Young and male

The party scored especially well with young, male voters, Van Grieken said — a trend that had been spotted by pollsters ahead of Sunday's votes.

“We’re the most popular party with young people, and political scientists agonize over why this is the case. It’s pretty simple: We had terror attacks [in Brussels in 2016], the biggest migration crisis,” he said. He added that Belgium's integration policy encourages cultural diversity but also causes resentment among some Flemish youngsters "who say ‘We want to experience our culture.’”

If one single candidate epitomizes how Vlaams Belang won over young voters, it's Dries Van Langenhove.

A 26-year-old who recently aligned himself to the party as an independent candidate, Van Langenhove gained national prominence as leader of an extreme-right youth movement called Shield and Friends, which is part of a broader phenomenon of so-called "Generation Identity" groups cropping up across Europe.

Last September, an investigation by Belgian public broadcaster VRT documented how Van Langenhove’s group was running blatantly anti-Semitic and racist online chatrooms on platforms like Facebook and the gaming app Discord — flirting with neo-Nazi ideology and memes linked to the U.S. alt-right movement.

The investigation shocked many Belgians. But Van Langenhove dismissed accusations and said the investigation misrepresented him, and used the spotlight to his own advantage, rallying young, far-right sympathizers at universities and elsewhere behind him. Then Vlaams Belang announced in January that it had recruited the extreme-right youngster to lead its list of candidates in one of Flanders’ five provincial constituencies.

“Polls show I score very well with Flemish youth — even that I'm the most popular politician with that group,” Van Langenhove told POLITICO. Asked about his attachment to the identitarian movement Shield and Friends, he said: “Shield and Friends remains the future if you ask me. A real change in mentality with the Flemish youth remains necessary.”

Social spending

While Van Langenhove faced criticism, scrutiny and expressions of revulsion from the mainstream media and political figures, he performed well on social media.

"What I do, my job, I can't do it without social media," Van Langenhove said, adding that his new seat in Belgium's federal parliament would help protect him from censorship for hate speech on platforms like Facebook.

Facebook, YouTube, Twitter and other platforms have come under criticism around the world in recent years for boosting fringe and radical groups in the political debate at the expense of moderates. These companies have tried to turn the tide by tweaking algorithms to repress messages that incite hatred. In the past year, under pressure from political leaders in Europe and elsewhere, they have also increasingly blocked and banned political figures who have violated their rules against spreading hate speech.

In Belgium, Vlaams Belang has been more effective than probably any other party in concentrating its message — and campaign budget — on Facebook and other online platforms to spread its message.

Public broadcaster VRT calculated that Vlaams Belang's expenditure on social media was double that of the country's largest (and richest) party, the New Flemish Alliance. The latter also spent half its online budget on Google ads, which Vlaams Belang didn't do. In total, Vlaams Belang spent nearly as much on Facebook and Google as all of the other Flemish parties combined.

The man behind that online campaign, Bart Claes, has spent years working outside of the public eye to build up an audience and test tools targeting subgroups of Flemish voters sensitive to the party’s radical-right messaging.

For inspiration, Claes turned to Brexit and the Trump campaign. “For some time I was really obsessed about these campaigns,” Claes told POLITICO, adding that he had devoured books and documentaries on how these U.K. and U.S. political shocks were delivered to study their potential application in Flanders.

It was clear to him that Vlaams Belang's particular message sticks more easily with social media audiences.

“This is the scroll generation. People have an attention span of one, maybe two seconds. Within that time a message has to be clear, and that’s easier for a party with clear positions than it is for parties in the [political] center,” he said.

Ad campaign

Claes said he and another social media team member looked for ways to identify those potential voters. They came up with a social media strategy that, he said, reached 1.5 million Flemish people per day during the campaign whom the party could attempt to sway in its favor.

Facebook’s ads library reveals a social media strategy that was focused on the final weeks of the election campaign, and mostly targeted young voters aged 18 to 34.

The Flemish far-right party spent €400,551 on ad campaigns on Facebook and Instagram between March and May 25, according to the ads library. Over €125,000 of that was spent during the last week before the election.

A 20-minute video of party leader Tom Van Grieken railing against migration that was circulated one week before the election reached up to 1 million Facebook users. Over half of them were aged under 34 and nearly 70 percent were male.

Other ads had an even more targeted audience: A last-minute Instagram ad that asked followers to tag undecided voters among their friends was displayed between 10,000 and 50,000 times over two days; 63 percent of the people who saw it were men aged 18 to 24, while 24 percent were young women in the same age bracket.

Claes said the party invested very little money in paper posters and flyers, saying it is “expensive and a little outdated.”

Second coming

Sunday's far-right win reminded Belgians of one of the key moments in its recent political history, known as “Black Sunday.”

In 1991, the far-right party — which at the time was still known as Vlaams Blok (Flemish Bloc) — had its breakthrough moment when it won 6.6 percent of the Flemish vote. It was a shock to the Belgian political establishment.

“We were young chaps who, out of nowhere, conjured up a new party,” said Gerolf Annemans, the party’s éminence grise at European level, its president until 2014, and for long time one of its leading figures.

The party rose on a platform of extreme-right proposals such as abolishing "multicultural indoctrination" in schools, setting up a “foreigners' police” charged with tracking down illegal immigrants in Belgium, and a series of limitations on the rights of foreigners in the country.

Black Sunday triggered a backlash against the far right among traditional parties, who promised to prevent Vlaams Blok from ever getting into a position of power. They argued that its doctrines were dangerous for Belgian democracy, and for years the mainstream media excluded its members from panels and interviews.

However, the country-wide cordon sanitaire didn’t stop the party from growing. A racism conviction in 2004 by Belgium's courts triggered record support of 24.2 percent in a Flemish regional election, but soon after forced the party to be dissolved, though it quickly regrouped under its new name Vlaams Belang.

Between 2004 and 2014, a large part of its electorate shifted to the New Flemish Alliance, whose line on migration is tough but more moderate than Vlaams Belang's proposals. When the far-right party suffered further losses in the "triple vote" of 2014, Annemans passed the baton to Van Grieken and his generation.

On Sunday, they succeeded in yanking Flemish politics sharply to the right once more, causing huge headaches for mainstream parties looking to form the new government, and wider concern among Belgian society about the radicalization of politics in the largely prosperous north of the country.

Hanne Cokelaere and Simon Van Dorpe contributed reporting.

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