Four Democratic U.S. senators have accused X of giving prediction market Polymarket preferential treatment in its advertising system. According to Foresight News, Semafor reported that Catherine Cortez Masto, Adam Schiff, Jacky Rosen and Richard Blumenthal jointly sent a letter raising the allegation. They said users reporting Polymarket ads through X’s standard interface could not select a reporting option, while ads from other platforms, including Kalshi, could be reported normally.

The senators said the apparent preferential treatment raised questions about whether X was giving Polymarket an unfair competitive advantage and benefiting U.S. President Donald Trump and his family. Donald Trump Jr. is an investor and adviser to Polymarket. X and Polymarket did not respond to requests for comment.