Since taking office, President Trump has threatened European countries’ security and economies, angled to take control of Greenland, and promised to “definitely” slap the nations with tariffs. Even parties that would seem to be his natural allies are nervous. Some have quietly tiptoed back from the American president.

But Saturday was not the day for disputes. Leaders of far-right parties in Europe came to Madrid for what, on the surface at least, amounted to a boldface names booster rally for a new Trump era.

There was Marine Le Pen of France’s far-right National Rally; the Netherland’s populist, Geert Wilders; the leader of Italy’s League party, Matteo Salvini. All made clear that they shared Mr. Trump’s charge against what they see as “wokeism,” “gender theory,” and overweening environmentalism.

For them, the American president had blown through the last barriers that had confined their parties to the political margins. The taboos had been toppled.

“Trump’s tornado has changed the world in just a couple of weeks,” Prime Minister Viktor Orban of Hungary told his allies from the stage of the summit whose slogan was, “Make Europe Great Again.”

“Yesterday we were the heretics,” he said. “Now we are the mainstream.”