Dozens of Facebook groups bill themselves as Kamala Harris fan pages but mount racist attacks, criticize her record on immigration and promote her rival Donald Trump, in what disinformation researchers call a "bait-and-switch" tactic aimed at deceiving voters in a tight U.S. election race.

The Washington-based American Sunlight Project analyzed over 300 groups on the Meta-owned platform that masquerade as pro-Harris pages while misleading the Democratic contender's supporters with abusive, hateful posts or capitalize on her popularity to promote merchandise.

The proliferation of such Facebook groups, which typically bring together communities with shared interests, does not appear to be an organized effort and illustrates a sophisticated tactic to seed false election narratives in trusted online spaces.