But Mr. Putin’s savaging of Ukraine, which many of his right-wing supporters had said he would never do, has recast the Russian president more clearly as a global menace and boogeyman with ambitions of empire who is threatening nuclear war and European instability.

For many of his longtime admirers — from France to Germany and the United States to Brazil — it is something of an awkward spot. The stain of Mr. Putin’s new reputation threatens to taint his fellow travelers, too.

“It will be a decisive blow to them,” said Lucio Caracciolo, the editor of the Italian geopolitical magazine Limes, who considered Mr. Putin’s invasion an irrational, and potentially, a politically suicidal move. He said that members of the international ultraright who enjoyed a special relationship and financial support from Mr. Putin were “in serious trouble.” “They put all their eggs in the same basket,” Mr. Caracciolo said. “And the basket is collapsing.”