BRUSSELS — For weeks, Europe’s far-right populists have been dashing across the Continent, joining arms and presenting themselves as a united front that will batter the political establishment and score a big breakthrough in this week’s elections for the European Parliament.

Their latest group hug came in Milan on Saturday evening, where Italy’s firebrand, Matteo Salvini, preened with France’s far right icon, Marine Le Pen, and nearly a dozen other populist leaders. They bashed the European Union, migrants and Islam and promised the dawn of a new, nationalist era.

But it was telling what they did not talk about: the scandal that erupted this weekend in Austria, which led to the collapse of the nation’s coalition government after the far-right vice chancellor was caught on a video promising favors to a woman claiming to be a Russian investor.

The scandal has rocked Austria. The vice chancellor, a leader of the far-right Freedom Party, quickly resigned, and new elections have been called for September. But it is also rippling across Europe, only days before the European parliamentary elections, as a reminder that Russia has deep ties to many other populist parties, too.