“Trump has become a savior figure, a sort of great redeemer for the German far right,” said Miro Dittrich, an expert on far-right extremism at the Berlin-based Amadeu-Antonio-Foundation.

Germany — a nation generally supportive of a government that has handled the pandemic better than most — may seem an unlikely place for Mr. Trump to gain such a status. Few Western nations have had a more contentious relationship with Mr. Trump than Germany, whose leader, Chancellor Angela Merkel, a pastor’s daughter and scientist, is his opposite in terms of values and temperament. Opinion polls show that Mr. Trump is deeply unpopular among a broad majority of Germans.

But his message of disruption — his unvarnished nationalism and tolerance of white supremacists coupled with his skepticism of the pandemic’s dangers — is spilling well beyond American shores, extremism watchers say.