The news that Mr Donald Trump has in effect secured the Republican party's nomination for the United States presidency took me back to Europe in 2002.
Back then it was a huge shock when Mr Jean-Marie Le Pen, a far-right candidate, made it through to the last two in the French presidential election. I remember going to the European Union (EU) press room in Brussels the morning after Mr Le Pen's initial success, and witnessing the horror and shame of my French colleagues.
The good news is that Mr Le Pen was soundly beaten in the final round. The bad news is that, in retrospect, his breakthrough marked a turning point in European politics. Ever since 2002, the themes that Mr Le Pen championed - nationalism, a hatred of immigration, denunciation of "unpatriotic" elites, fear of Islam, rejection of the EU, protectionism - have grown in strength in Europe.
The far right has not yet formed a government in western Europe. But it has changed the debate and forced mainstream politicians to embrace some of its themes.
I fear that the same thing will happen with Mr Trump. The odds are that the "Republican" (if that is what he is) will lose to Mrs Hillary Clinton in November. But the Trump campaign has already changed US and world politics - and it will make an even deeper imprint in the next six months of campaigning.
Themes and ideas that were on the fringes have now entered the political mainstream, and they will not disappear if and when Mr Trump loses.
What are those ideas? I would highlight five. First, a rejection of globalisation and free trade. This, of course, is a theme that Mr Trump shares with Mr Bernie Sanders on the left of the Democratic party. Its influence can already be seen in the way in which Mrs Clinton has backed away from the Trans-Pacific Partnership, a trade deal that she once championed.
The second theme is nationalism, epitomised by Mr Trump's slogan of "America First". In Europe, nationalism implies a rejection of the EU. But the global implications of American nationalism are much more serious since the US underpins the whole international security system and issues the world's reserve currency, the dollar.
A third idea is the embrace of the notion of a "clash of civilisations" between the West and Islam. Even as then President George W. Bush launched a "war on terror" in 2001, he rejected the idea that the US is at war with Islam itself. Mr Trump, with his talk of temporarily banning all Muslims from entering the US, has essentially embraced the idea of inevitable conflict between the West and the Islamic world.
A fourth theme is a relentless assault on the "elite", including Washington, Wall Street and the universities. A populist distrust of elites has been a perennial theme in US politics for decades, if not centuries. But growing inequality, immigration and the financial crisis have driven anti-elite rhetoric to new levels. As a New York billionaire, Mr Trump is an unlikely tribune of the common man. But he has played the card effectively during the campaign.
A fifth and related trend is the denunciation of the mainstream media as untrustworthy and an embrace of alternative, conspiratorial narratives that are flourishing on the Internet. Mr Trump, for example, has promoted the baseless idea that President Barack Obama was not born in the US. This embrace of conspiracy theories is pernicious for democracy, which requires some agreement on basic facts as the foundation for debate.
Variants of these five trends are also flourishing on the far right in Europe. The governments of Poland and Hungary are in the hands of parties that preach a Trumpian mix of nationalism, fear of Islam, distrust of the "liberal" media and anti-globalism. In France, Mr Le Pen's daughter, Marine, is likely to make it to the final round of the presidential election next year.
Some in the US may still flinch at the idea that a leading American politician belongs in the same ideological camp as France's National Front, a party with roots in fascism. But Mr Le Pen obviously sees the parallel and has tweeted his support for Mr Trump, adding "may God protect him". In fact, in some respects, Mr Trump's platform is more extreme than that of the French far right. Neither of the Le Pens has ever proposed banning all Muslims from entering France.
Mr Trump is also likely to be more electorally successful than the National Front. Mr Le Pen won less than 18 per cent of the vote in 2002. His daughter may double that total next year.
But Mr Trump, as the Republican party candidate, will almost certainly exceed 40 per cent of the national vote. It is possible, as with the Le Pens (and the Clintons and the Bushes), that we may also see the establishment of a Trump political dynasty. Who would rule out a bid for the presidency by Mr Trump's daughter, Ivanka, in eight years' time?
Many liberal Americans are still inclined to treat the Trump phenomenon as a nightmare from which they hope to wake up in November. But that seems highly unlikely. Mr Trump has now amply demonstrated the political potency of the ideas that he is promoting.
A rising generation of nationalists, in the US and Europe, will profit from his breakthrough.
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