Across Europe, parties that have won less than one-quarter of the national vote are redefining the parameters of public debate and bringing ideas and policies that were once beyond the pale into the mainstream. Since 2015, when nativist parties began to chalk up impressive electoral triumphs from Provence to Pennsylvania, there has been much hand-wringing among establishment politicians and left-wing voters in Europe and the United States.

Some breathed a sigh of relief after Emmanuel Macron’s 2017 victory over Marine Le Pen and the Dutch Prime Minister Mark Rutte’s defeat of Geert Wilders, taking solace in the refrain: “At least they didn’t win.” They should not be comforted. The fact is far-right parties don’t have to win to set the legislative agenda.

In Italy’s March election, Matteo Salvini, the leader of the League party and a hardline Eurosceptic and anti-immigration candidate, won just under 18 per cent of the vote, far less than the Five Star Movement’s 32 per cent. But it is Salvini — not Five Star leader Luigi Di Maio or the figurehead Prime Minister, Giuseppe Conte — who is in the driver’s seat.

When ships carrying hundreds of rescued refugees tried to dock in Italian ports, Salvini turned them away; ultimately Spain allowed one of the vessels to dock in Valencia. And despite the fact that Italy, along with Greece, has borne a disproportionate burden during the refugee crisis due to its geographic position, Salvini has in recent weeks been abandoning Italy’s national interests by making common cause with Eastern European leaders who refuse to accept quotas of refugees — precisely the sort of burden-sharing that could help relieve the pressure on Italy.

In Denmark, the harshly anti-immigrant Danish People’s party took 21 per cent of the vote in the 2015 election and ever since has masterfully manipulated the rest of the country’s politicians — forcing the centre-right Prime Minister Lars Lokke Rasmussen to push through many of their preferred policies, while dragging the centre-left Social Democrats, who fear losing even more working-class voters to the far right, along with them.

Because Denmark’s nativists have, like Marine Le Pen in France, combined xenophobic populism with a spirited defence of a generous welfare state, they’ve managed to siphon working-class voters away from the left. Earlier this year, Denmark’s Social Democrats endorsed the idea of offshore detention camps in North Africa to prevent refugees from ever setting foot on Danish soil — an Australian-inspired vision of putting asylum seekers out of sight and out of mind that has long been a fantasy of the European far right.

In Germany, the upstart Alternative for Germany party (AfD) won just 12.6 per cent of the national vote in 2017. Despite the party’s modest numbers in parliament, however, it is influencing the policies of Angela Merkel’s government by threatening to poach votes from her sister party, the Christian Social Union (CSU), in the state of Bavaria. The CSU has long been the only political player in town in the wealthy southern state where many refugees first arrived in Germany in late 2015.

As the AfD’s support base has grown, thanks to growing anti-immigrant sentiment, the CSU has scrambled to shore up its right flank in advance of state elections in October. As a consequence, the CSU Interior Minister, Horst Seehofer, has become a thorn in Merkel’s side, threatening to bring down her government. Merkel lived to fight another day, but not before Seehofer succeeded in forcing concessions earlier this month, when Merkel announced she would set up “transit camps” for migrants along the German border.

This is not an accident, it is the result of a conscious strategy on the part of the far-right’s leaders to pressure the CSU and CDU. When I interviewed Alexander Gauland, the AfD’s co-leader, in July 2016, he made it clear that the party’s immediate goal is to influence and drive debate rather than win power or join a coalition. Referring to left wing politicians who have adopted harsher rhetoric on immigration, he gleefully told me Germany’s “discussion has totally changed. This is what we have done”.

And in the United States, thanks to an electoral college victory that put him in the White House despite losing the popular vote to Hillary Clinton by nearly three million votes, Donald Trump has managed to implement policies that forcibly separated migrant children from their parents and banned the entry of visitors from certain Muslim-majority countries — until public outrage and the courts compelled him to slightly soften his stance on both fronts (in late June, the supreme court upheld a watered-down iteration of his travel ban).

Trump’s hostile takeover of the US Republican party and his effective control of all three branches of government has given him a free hand. In Europe, nativist parties have leveraged their minority status to force draconian immigration policies on centre-right and centre-left politicians who live in constant fear of losing voters to the far right. In so doing, nativist parties have created a new normal — bringing policies like turnbacks of refugee boats, offshore detention and family separations from the margins to the mainstream. It is an extremely effective form of political blackmail.

Some defenders of nativist populism claim that the backlash against immigrants and refugees is harmless. They regard it as decent and acceptable expression of citizens’ rage about immigration — a resentment ignored for too long by technocratic elites who didn’t have to live with the consequences of immigration. But the fact that some voters’ grievances are genuine does not mean that the solutions proposed by populist leaders are valid.

The writer is a British journalist