It’s not just Americans who are anxious about the election: The wave of populist conservative parties that surged across Europe after Donald Trump won are watching the U.S.

“A Trump victory is crucial to us,” said Ivan Espinosa de los Monteros, a top official in Spain’s upstart far-right nationalist Vox party.

Trump loses.

Some analysts say the beleaguered centrist and pro-EU integration parties that are now only clinging to power in several European nations, such as Germany, will likely rally around the loss to argue that the far right’s global surge of recent years — capped by the 2016 Brexit vote and Mr.

“European centrists will try to regain ground they lost while Trump was in office,” said Jeffrey Rathke, a former high-level U.S.

A Trump defeat, he added, would not only affect domestic politics in states across Europe, but will likely have major ramifications for collective European foreign policy.

“The ruling parties in Europe are going to try to consolidate parts of the trans-Atlantic relationship they thought were under assault while Trump was in office,” said Mr.

He also said the major powers within the EU are likely to seize on a Trump loss to re-engage as a bloc with Washington, rather than try to cut deal as individual states.

Rathke said, a Trump victory in November “will scare the bejesus out of Europe’s centrist politicians” and likely escalate polarization on the continent between multilateralists and nationalists.

“You’ll have the outsiders feeling like they’re back on the move again because Donald Trump pulled off another victory in the United States,” he said.

At the same time, a Trump loss would be devastating to the far-right parties pushing anti-elite agendas and, like Vox, seeking to sharply restrict immigration flows into Europe.

“The United States is the headliner for this activity under Trump, so if he loses in November, the headliner goes away,” said Gordon Adams, a longtime international affairs expert and professor emeritus at American University in Washington.

“The resonance of having the most powerful country in the world being run by somebody who is sympathetic to the far-right perspective would be a huge loss conceptually in terms of the credibility of what these parties trying to do in Europe,” Mr.

Will the lid on Pandora’s box be closed because Trump lost.

“Yes, these forces in Europe will lose the megaphone they currently have in Donald Trump and that will, to some degree, discredit what they’re trying to do,” Mr.

Espinosa said

Espinosa argued that the “elite progressives” of Western Europe will push to dominate the political agenda in countries like Spain by seeking to stifle conservative parties like Vox

Espinosa said