Campaigning for a seat in the European Parliament this spring, Lena Schilling was already facing an uphill battle, with her Green Party expected to fare poorly in the election across the continent.

Then came a devastating takedown by a major news media outlet attacking not her policies but her character, with the ensuing controversy possibly making an already difficult situation for the Greens even worse.

On May 7, Der Standard, one of Austria’s leading newspapers, published an article stating that Ms. Schilling, a 23-year-old whose climate activism had already given her a prominent national profile, “has a problematic relationship with the truth, plays people off each other and leaves a scorched earth in her wake.”

The next morning, Ms. Schilling defended herself at a news conference, saying the accusations had nothing to do “with politics or Europe or the upcoming elections.”

The article, which accused Ms. Schilling of spreading damaging rumors about colleagues and friends and manipulating fellow climate activists, generated significant attention in Austria, and powerful defenders and detractors of Ms. Schilling lined up on opposing sides.

Werner Kogler, Austria’s vice chancellor and the country’s Green Party spokesman, called the article “anonymous murmurs.” Austria’s president, Alexander Van der Bellen, offered his support.